|Part of a series on the|
COVID-19 vaccine clinical research is the clinical research on COVID-19 vaccines, including their efficacy, effectiveness and safety. There are 24 vaccines authorized for use by national governments, with six vaccines being approved for emergency or full use by at least one WHO-recognised stringent regulatory authority; and five of them are in Phase IV. 204 vaccines under clinical trials that have not yet been authorized. There are also nine clinical trials on heterologous vaccination courses.
In Phase III trials, several COVID‑19 vaccines have demonstrated efficacy as high as 95% in preventing symptomatic COVID‑19 infections. Twenty vaccines are authorized by at least one national regulatory authority for public use: one DNA vaccine (ZyCoV-D) two RNA vaccines (Pfizer–BioNTech and Moderna), ten conventional inactivated vaccines (BBIBP-CorV, Chinese Academy of Medical Sciences, CoronaVac, Covaxin, CoviVac, COVIran Barekat, FAKHRAVAC, Minhai-Kangtai, QazVac, and WIBP-CorV), five viral vector vaccines (Sputnik Light, Sputnik V, Oxford–AstraZeneca, Convidecia, and Janssen), and six subunit vaccines (Abdala, COVAX-19, EpiVacCorona, MVC-COV1901, Soberana 02, and ZF2001). I trials, 30 in Phase I–II trials, 25 in Phase III trials, and 8 in Phase IV development.In total, 330 vaccine candidates are in various stages of development, with 102 in clinical research, including 30 in Phase
This section's factual accuracy may be compromised due to out-of-date information.(August 2021)
As of September 2020 [update] , eleven of the vaccine candidates in clinical development use adjuvants to enhance immunogenicity. An immunological adjuvant is a substance formulated with a vaccine to elevate the immune response to an antigen, such as the COVID‑19 virus or influenza virus. Specifically, an adjuvant may be used in formulating a COVID‑19 vaccine candidate to boost its immunogenicity and efficacy to reduce or prevent COVID‑19 infection in vaccinated individuals. Adjuvants used in COVID‑19 vaccine formulation may be particularly effective for technologies using the inactivated COVID‑19 virus and recombinant protein-based or vector-based vaccines. Aluminum salts, known as "alum", were the first adjuvant used for licensed vaccines, and are the adjuvant of choice in some 80% of adjuvanted vaccines. The alum adjuvant initiates diverse molecular and cellular mechanisms to enhance immunogenicity, including release of proinflammatory cytokines.
Phase I trials test primarily for safety and preliminary dosing in a few dozen healthy subjects, while Phase II trials –following success in Phase I –evaluate immunogenicity, dose levels (efficacy based on biomarkers) and adverse effects of the candidate vaccine, typically in hundreds of people. A Phase I–II trial consists of preliminary safety and immunogenicity testing, is typically randomized, placebo-controlled, while determining more precise, effective doses. Phase III trials typically involve more participants at multiple sites, include a control group, and test effectiveness of the vaccine to prevent the disease (an "interventional" or "pivotal" trial), while monitoring for adverse effects at the optimal dose. Definition of vaccine safety, efficacy, and clinical endpoints in a Phase III trial may vary between the trials of different companies, such as defining the degree of side effects, infection or amount of transmission, and whether the vaccine prevents moderate or severe COVID‑19 infection.
A clinical trial design in progress may be modified as an "adaptive design" if accumulating data in the trial provide early insights about positive or negative efficacy of the treatment. II–III clinical trials on candidate vaccines may shorten trial durations and use fewer subjects, possibly expediting decisions for early termination or success, avoiding duplication of research efforts, and enhancing coordination of design changes for the Solidarity trial across its international locations.Adaptive designs within ongoing Phase
National regulatory authorities have granted emergency use authorizations for twenty-two vaccines. Six of those have been approved for emergency or full use by at least one WHO-recognized stringent regulatory authority. Biologic License Applications for the Pfizer–BioNTech and Moderna COVID‑19 vaccines have been submitted to the US Food and Drug Administration (FDA).
The table below shows various vaccines authorized either for full or emergency use so far, with various other details.
|COVID-19 vaccines authorized for emergency use or approved for full use|
The table below shows various vaccine candidates and the phases which they have completes so far. Current phases are also shown along with other details.
|COVID‑19 candidate vaccines in Phase I–III trials|
In July 2021, the U.S. Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) issued a joint statement reporting that a booster dose is not necessary for those who have been fully vaccinated.
In August 2021, the FDA and the CDC authorized the use of an additional mRNA vaccine dose for immunocompromised individuals.The authorization was extended to cover other specific groups in September 2021.
In October 2021, the FDA and the CDC authorized the use of either homologous or heterologous vaccine booster doses.
In October 2021, the US Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) authorized the use of either homologous or heterologous vaccine booster doses.
Some experts believe that heterologous prime-boost vaccination courses can boost immunity, and several studies have begun to examine this effect.Despite the absence of clinical data on the efficacy and safety of such heterologous combinations, Canada and several European countries have recommended a heterologous second dose for people who have received the first dose of the Oxford–AstraZeneca vaccine.
In February 2021, the Oxford Vaccine Group launched the Com-COV vaccine trial to investigate heterologous prime-boost courses of different COVID-19 vaccines.As of June 2021, the group is conducting two phase II studies: Com-COV and Com-COV2.
In Com-COV, the two heterologous combinations of the Oxford–AstraZeneca and Pfizer–BioNTech vaccines were compared with the two homologous combinations of the same vaccines, with an interval of 28 or 84 days between doses. [ unreliable medical source? ]
In Com-COV2, the first dose is the Oxford–AstraZeneca vaccine or the Pfizer vaccine, and the second dose is the Moderna vaccine, the Novavax vaccine, or a homologous vaccine equal to the first dose, with an interval of 56 or 84 days between doses.
A study in the UK is evaluating annual heterologous boosters by randomly selecting the following vaccines: Oxford–AstraZeneca, Pfizer–BioNTech, Moderna, Novavax, VLA2001, CureVac, and Janssen.
|First dose||Second dose||Schedules||Current phase (participants), periods and locations|
| Oxford–AstraZeneca |
| Oxford–AstraZeneca |
|Days 0 and 28|
Days 0 and 84
|Phase II (820)|
Feb–Aug 2021, United Kingdom
|Phase II (121)|
Feb–Aug 2021, Argentina
|Days 0 and 56–84||Phase II (1,050)|
Mar 2021 –Sep 2022, United Kingdom
|Convidecia||ZF2001||Days 0 and 28|
Days 0 and 56
|Phase IV (120)|
Apr–Dec 2021, China
|Oxford–AstraZeneca||Pfizer–BioNTech||Days 0 and 28||Phase II (676)|
Apr 2021 –Apr 2022, Spain
|Days 0 and 28|
Days 0 and 112
|Phase II (1,200)|
May 2021 –Mar 2023, Canada
|Days 0 and 42||Phase II (400)|
May 2021 –Jan 2022, France
|Oxford–AstraZeneca||Pfizer–BioNTech||Days 0 and 28|
Days 0 and 21–49
|Phase II (3,000)|
May–Dec 2021, Austria
|Days 0 and 84||Phase II (432)|
Jun 2021 –Sep 2022, Netherlands
Vaccine efficacy is the reduction in risk of getting the disease by vaccinated participants in a controlled trial compared with the risk of getting the disease by unvaccinated participants. [ citation needed ]An efficacy of 0% means that the vaccine does not work (identical to placebo). An efficacy of 50% means that there are half as many cases of infection as in unvaccinated individuals.
COVID-19 vaccine efficacy may be adversely affected if the arm is held improperly or squeezed so the vaccine is injected subcutaneously instead of into the muscle.The CDC guidance is to not repeat doses that are administered subcutaneously.
It is not straightforward to compare the efficacies of the different vaccines because the trials were run with different populations, geographies, and variants of the virus.In the case of COVID‑19 prior to the advent of the delta variant, it was thought that a vaccine efficacy of 67% may be enough to slow the pandemic, but the current vaccines do not confer sterilizing immunity, which is necessary to prevent transmission. Vaccine efficacy reflects disease prevention, a poor indicator of transmissibility of SARS‑CoV‑2 since asymptomatic people can be highly infectious. The US Food and Drug Administration (FDA) and the European Medicines Agency (EMA) set a cutoff of 50% as the efficacy required to approve a COVID‑19 vaccine, with the lower limit of the 95% confidence interval being greater than 30%. Aiming for a realistic population vaccination coverage rate of 75%, and depending on the actual basic reproduction number, the necessary effectiveness of a COVID-19 vaccine is expected to need to be at least 70% to prevent an epidemic and at least 80% to extinguish it without further measures, such as social distancing.
The observed substantial efficacy of certain mRNA vaccines even after partial (1-dose) immunizationindicates a non-linear dose-efficacy relation already seen in the phase I-II study and suggests that personalization of the vaccine dose (regular dose to the elderly, reduced dose to the healthy young, additional booster dose to the immunosuppressed ) might allow accelerating vaccination campaigns in settings of limited supplies, thereby shortening the pandemic, as predicted by pandemic modeling.
Ranges below are 95% confidence intervals unless indicated otherwise, and all values are for all participants regardless of age, according to the references for each of the trials. By definition, the accuracy of the estimates without an associated confidence interval is unknown publicly. Efficacy against severe COVID-19 is the most important, since hospitalizations and deaths are a public health burden whose prevention is a priority.Authorized and approved vaccines have shown the following efficacies:
|COVID-19 vaccine efficacy|
As of August 2021, data from studies in the U.S. and in other countries found that the COVID-19 vaccines available in the United States are "highly protective against severe illness, hospitalization, and death due to COVID-19".In comparison with fully vaccinated people, the CDC found that unvaccinated people were 5 times more likely to be infected, 10 times more likely to be hospitalized, and 11 times more likely to die.
By late August 2021, after the Delta variant became dominant, studies concluded that COVID-19 vaccines provided 55 percent protection against infection, 80 percent against symptomatic infection, and at least 90 percent against hospitalization. [ medical citation needed ] The Delta variant, which is about 40 percent more contagious than the alpha variant, [ medical citation needed ] became the dominant strain during the spring of 2021. However, the vaccines still protected against severe illness and hospitalizations with slight reduction in effectiveness. [ medical citation needed ] The CDC similarly found that vaccines were 90 percent effective at preventing hospitalizations.
As a result of the CDC reports, President Joe Biden said that "virtually all" COVID-19 hospitalizations and deaths in the U.S. were among unvaccinated people.A study in the state of Washington found that unvaccinated people were six times more likely to test positive for COVID-19, 37 times more likely to be hospitalized, and 67 times more likely to die, compared to those who had been vaccinated.
Researchers note that although current vaccines were not designed against the Delta variant, they nonetheless are highly effective, but to a lesser degree: protection fell from 91% to 66%. [ unreliable source? ][ medical citation needed ] One expert stated that "those who are infected following vaccination are still not getting sick and not dying like was happening before vaccination." "This virus is the most efficient virus for finding new hosts that are vulnerable," stated Dr. Eric Topol, director and founder of the Scripps Research Translational Institute. By late August 2021 the Delta variant accounted for 99 percent of U.S. cases and was found to double the risk of severe illness and hospitalization for those not yet vaccinated.
In September 2021, the European Journal of Epidemiology published a study demonstrating that increases in COVID-19 are unrelated to levels of vaccination across 68 countries and 2947 counties in the United States. The study also indicated that the trend line suggests a marginally positive association such that countries with a higher percentage of their population fully vaccinated have higher COVID-19 cases per 1 million people. The authors of the study advised that sole reliance on vaccination as a primary strategy to mitigate COVID-19 and its adverse consequences needs to be re-examined, especially considering the Delta variant and the likelihood of future variants.
The real-world studies of vaccine effectiveness measure to which extent a certain vaccine has succeeded in preventing COVID-19 infection, symptoms, hospitalization and death for the vaccinated individuals in a large population under routine conditions that are less than ideal.
|Vaccine||Effectiveness by severity of COVID-19||Study location||Refs|
|Oxford–AstraZeneca||≈70% (69–71%)||Not reported||≈87% (85–88%)||≈90% (88–92%)||Brazil||[ unreliable medical source? ]|
|Not reported||≈89% (78–94%)||Not reported||England|
|Pfizer–BioNTech||≈92% (91–92%)||≈97% (97–97%)||≈98% (97–98%)||≈97% (96–97%)||Israel|
|≈92% (88–95%)||≈94% (87–98%)||≈87% (55–100%)||≈97%||Israel|
|Not reported||≈78% (77–79%)||≈98% (96–99%)||≈96% (95–97%)||Uruguay|
|≈85% (74–96%)||Not reported||England|
|≈90% (68–97%)||Not reported||≈100%||United States|
|Moderna||≈90% (68–97%)||Not reported||≈100%||United States|
|≈50% (49–52%)||Not reported||≈94% (91–96%)||Peru|
|Sputnik V||Not reported||≈98%||Not reported||Russia|
|Not reported||≈98%||≈100%||≈100%||United Arab Emirates|
|CoronaVac||≈54% (53–55%)||Not reported||≈73% (72–74%)||≈74% (73–75%)||Brazil|
|Not reported||≈66% (65–67%)||≈88% (87–88%)||≈86% (85–88%)||Chile|
|Not reported||≈60% (59–61%)||≈91% (89–93%)||≈95% (93–96%)||Uruguay|
|Sputnik Light||≈79% (75–82%)||Not reported||≈88% (80–92%)||≈85% (75–91%)||Argentina|
While the most immediate goal of vaccination during a pandemic is to protect individuals from severe disease, a long-term goal is to eventually eradicate it. To do so, the proportion of the population that must be immunized must be greater than the critical vaccination coverage . This value can be calculated from the basic reproduction number and the vaccine effectiveness against transmission as:
Assuming R0 ≈ 2.87 for SARS-CoV-2,then, for example, the coverage level would have to be greater than 72.4% for a vaccine that is 90% effective against transmission. Using the same relationship, the required effectiveness against transmission can be calculated as:
Assuming the same R0 ≈ 2.87, the effectiveness against transmission would have to be greater than 86.9% for a realistic coverage level of 75%or 65.2% for an impossible coverage level of 100%. Less effective vaccines would not be able to eradicate the disease.
Several post-marketing studies have already estimated the effectiveness of some vaccines against asymptomatic infection. Prevention of infection has an impact on slowing transmission (particularly asymptomatic and pre-symptomatic), but the exact extent of this effect is still under investigation.
Some variants of SARS-CoV-2 are more transmissible, showing an increased effective reproduction number, indicating an increased basic reproduction number. Controlling them requires greater vaccine coverage, greater vaccine effectiveness against transmission, or a combination of both.
In July 2021, several experts expressed concern that achieving herd immunity may not currently be possible because the Delta variant is transmitted among those immunized with current vaccines.The CDC published data showing that vaccinated people could transmit the Delta strain, something officials believed was not possible with other variants.
This section's factual accuracy may be compromised due to out-of-date information. The reason given is: Information taken from WHO's COVID-19 Weekly Epidemiological Update is outdated and inaccurate. The latest version now is 20 July, edition 49.(July 2021)
The interplay between the SARS-CoV-2 virus and its human hosts was initially natural but is now being altered by the prompt availability of vaccines. As of February 2021 [update] , the US Food and Drug Administration believed that all FDA authorized vaccines remained effective in protecting against circulating strains of SARS-CoV-2.The potential emergence of a SARS-CoV-2 variant that is moderately or fully resistant to the antibody response elicited by the COVID-19 vaccines may necessitate modification of the vaccines. The emergence of vaccine-resistant variants is more likely in a highly vaccinated population with uncontrolled transmission. Trials indicate many vaccines developed for the initial strain have lower efficacy for some variants against symptomatic COVID-19.
Limited evidence from various preliminary studies reviewed by the WHO indicated retained efficacy/effectiveness against disease from Alpha with the Oxford–AstraZeneca vaccine, Pfizer–BioNTech and Novavax, with no data for other vaccines yet. Relevant to how vaccines can end the pandemic by preventing asymptomatic infection, they have also indicated retained antibody neutralization against Alpha with most of the widely distributed vaccines (Sputnik V, Pfizer–BioNTech, Moderna, CoronaVac, BBIBP-CorV, Covaxin), minimal to moderate reduction with the Oxford–AstraZeneca and no data for other vaccines yet.
In December 2020, a new SARS‑CoV‑2 variant, the Alpha variant or lineage B.1.1.7, was identified in the UK.
Early results suggest protection to the variant from the Pfizer-BioNTech and Moderna vaccines.
One study indicated that the Oxford–AstraZeneca COVID-19 vaccine had an efficacy of 42–89% against Alpha, versus 71–91% against other variants. [ unreliable medical source? ]
Preliminary data from a clinical trial indicates that the Novavax vaccine is ~96% effective for symptoms against the original variant and ~86% against Alpha.
Limited evidence from various preliminary studies reviewed by the WHO have indicated reduced efficacy/effectiveness against disease from Beta with the Oxford–AstraZeneca vaccine (possibly substantial), Novavax (moderate), Pfizer–BioNTech and Janssen (minimal), with no data for other vaccines yet. Relevant to how vaccines can end the pandemic by preventing asymptomatic infection, they have also indicated possibly reduced antibody neutralization against Beta with most of the widely distributed vaccines (Oxford–AstraZeneca, Sputnik V, Janssen, Pfizer–BioNTech, Moderna, Novavax; minimal to substantial reduction) except CoronaVac and BBIBP-CorV (minimal to modest reduction), with no data for other vaccines yet.
Moderna has launched a trial of a vaccine to tackle the Beta variant or lineage B.1.351. April 2021, an update on a Pfizer/BioNTech South African vaccine trial stated that the vaccine was 100% effective so far (i.e., vaccinated participants saw no cases), with six of nine infections in the placebo control group being the Beta variant.On 17 February 2021, Pfizer announced neutralization activity was reduced by two-thirds for this variant, while stating that no claims about the efficacy of the vaccine in preventing illness for this variant could yet be made. Decreased neutralizing activity of sera from patients vaccinated with the Moderna and Pfizer-BioNTech vaccines against Beta was later confirmed by several studies. On 1
In January 2021, Johnson & Johnson, which held trials for its Janssen vaccine in South Africa, reported the level of protection against moderate to severe COVID-19 infection was 72% in the United States and 57% in South Africa.
On 6 February 2021, the Financial Times reported that provisional trial data from a study undertaken by South Africa's University of the Witwatersrand in conjunction with Oxford University demonstrated reduced efficacy of the Oxford–AstraZeneca COVID-19 vaccine against the variant. February 2021, the Minister for Health for South Africa suspended the planned deployment of about a million doses of the vaccine whilst they examine the data and await advice on how to proceed.The study found that in a sample size of 2,000 the AZD1222 vaccine afforded only "minimal protection" in all but the most severe cases of COVID-19. On 7
In March 2021, it was reported that the "preliminary efficacy" of the Novavax vaccine (NVX-CoV2373) against Beta for mild, moderate, or severe COVID-19 [ medical citation needed ]for HIV-negative participants is 51%.
Limited evidence from various preliminary studies reviewed by the WHO have indicated likely retained efficacy/effectiveness against disease from Gamma with CoronaVac and BBIBP-CorV, with no data for other vaccines yet. Relevant to how vaccines can end the pandemic by preventing asymptomatic infection, they have also indicated retained antibody neutralization against Gamma with Oxford–AstraZeneca and CoronaVac (no to minimal reduction) and slightly reduced neutralization with Pfizer–BioNTech and Moderna (minimal to moderate reduction), with no data for other vaccines yet.
The Gamma variant or lineage P.1 variant (also known as 20J/501Y.V3), initially identified in Brazil, seems to partially escape vaccination with the Pfizer-BioNTech vaccine.
Limited evidence from various preliminary studies reviewed by the WHO have indicated likely retained efficacy/effectiveness against disease from Delta with the Oxford–AstraZeneca vaccine and Pfizer–BioNTech, with no data for other vaccines yet. Relevant to how vaccines can end the pandemic by preventing asymptomatic infection, they have also indicated reduced antibody neutralization against Delta with single-dose Oxford–AstraZeneca (substantial reduction), Pfizer–BioNTech and Covaxin (modest to moderate reduction), with no data for other vaccines yet.
In October 2020, a new variant was discovered in India, which was named lineage B.1.617. There were very few detections until January 2021, but by April it had spread to at least 20 countries in all continents except Antarctica and South America.Mutations present in the spike protein in the B.1.617 lineage are associated with reduced antibody neutralization in laboratory experiments. The variant has frequently been referred to as a 'Double mutant', even though in this respect it is not unusual. the latter two of which may cause it to easily avoid antibodies. In an update on 15 April 2021, PHE designated lineage B.1.617 as a 'Variant under investigation', VUI-21APR-01. On 6 May 2021, Public Health England escalated lineage B.1.617.2 from a Variant Under Investigation to a Variant of Concern based on an assessment of transmissibility being at least equivalent to the Alpha variant.
One study found that the in vitro concentration (titer) of neutralizing antibodies elicited by a COVID-19 vaccine is a strong correlate of immune protection. The relationship between protection and neutralizing activity is nonlinear. A neutralization as low as 3% (95% CI, 1–13%) of the level of convalescence results in 50% efficacy against severe disease, with 20% (14–28%) resulting in 50% efficacy against detectable infection. Protection against infection quickly decays, leaving individuals susceptible to mild infections, while protection against severe disease is largely retained and much more durable. The observed half-life of neutralizing titers was 65 days for mRNA vaccines (Pfizer–BioNTech, Moderna) during the first 4 months, increasing to 108 days over 8 months. Greater initial efficacy against infection likely results in a higher level of protection against serious disease in the long term (beyond 10 years, as seen in other vaccines such as smallpox, measles, mumps, and rubella), although the authors acknowledge that their simulations only consider protection from neutralizing antibodies and ignore other immune protection mechanisms, such as cell-mediated immunity, which may be more durable. This observation also applies to efficacy against variants and is particularly significant for vaccines with a lower initial efficacy; for example, a 5-fold reduction in neutralization would indicate a reduction in initial efficacy from 95% to 77% against a specific variant, and from a lower efficacy of 70% to 32% against that variant. For the Oxford–AstraZeneca vaccine, the observed efficacy is below the predicted 95% confidence interval. It is higher for Sputnik V and the convalescent response, and is within the predicted interval for the other vaccines evaluated (Pfizer–BioNTech, Moderna, Janssen, CoronaVac, Covaxin, Novavax).
This section needs expansion. You can help by adding to it. (July 2021)
Serious adverse events associated with receipt of new vaccines targeting COVID-19 are of high interest to the public. [ citation needed ]All vaccines that are administered via intramuscular injection, including COVID-19 vaccines, have side effects related to the mild trauma associated with the procedure and introduction of a foreign substance into the body. These include soreness, redness, rash, and inflammation at the injection site. Other common side effects include fatigue, headache, myalgia (muscle pain), and arthralgia (joint pain) which generally resolve within a few days. One less-frequent side effect (that generally occurs in less than 1 in 1,000 people) is hypersensitivity (allergy) to one or more of the vaccine's ingredients, which in some rare cases may cause anaphylaxis. More serious side effects are very rare because a vaccine would not be approved even for emergency use if it had any known frequent serious adverse effects.
Most countries operate some form of adverse effects reporting scheme, for example Vaccine Adverse Event Reporting System in the United States and the Yellow Card Scheme [ citation needed ] of adverse effects.in the United Kingdom. In some of these, the data is open to public scrutiny, for example, in the UK, a weekly summary report is published. Concerns have been raised regarding both over- and under-reporting
In the UK, as of 22 September 2021, following the administering of over 48 million first vaccine doses and over 44 million second vaccine doses, there had been 347,447 suspected Covid-19 vaccine related events ('suspected adverse reactions', or 'ADRs') recorded in the Yellow Card system. The majority of these were reports of relatively minor effects (local reactions or temporary flu-like symptoms). Among more serious ADRs, the largest case load came from suspected thrombo-embolic events, of which a total of 439 were recorded, 74 of these fatal.A total of 1,682 suspected fatal ADRs were recorded. For comparison, at this date, the UK had had over 7,500,000 confirmed cases of Covid-19 and over 136,000 people had died within 28 days of a positive test for coronavirus.
The Janssen COVID-19 vaccine reported rare formation of blood clots in the blood vessels in combination with low levels of blood platelets known as thrombosis with thrombocytopenia syndrome (TTS) which occurred at a rate of about 7 per 1 million vaccinated women ages 18–49 years old; and even more rarely for other populations.According to the CDC, very rare cases of myocarditis and pericarditis have been reported in the United States, in about 13 per million young people (mostly in males and mostly over the age of 16), after vaccination with the Pfizer–BioNTech's or Moderna's vaccines. According to reports, the recovery from these rare side effects is quick in most individuals, following adequate treatment and rest.
In a study on the serologic response to COVID-19 messenger RNA vaccines among patients with lymphoma, leukemia and myeloma, it was found that one-quarter of patients did not produce measurable antibodies, varying by blood cancer type. Patients with these conditions need to take precautions to avoid exposure to COVID-19.
A COVID‑19 vaccine is a vaccine intended to provide acquired immunity against severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2), the virus that causes coronavirus disease 2019 (COVID‑19). Prior to the COVID‑19 pandemic, an established body of knowledge existed about the structure and function of coronaviruses causing diseases like severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). This knowledge accelerated the development of various vaccine platforms during early 2020. The initial focus of SARS-CoV-2 vaccines was on preventing symptomatic, often severe illness. On 10 January 2020, the SARS-CoV-2 genetic sequence data was shared through GISAID, and by 19 March, the global pharmaceutical industry announced a major commitment to address COVID-19. The COVID‑19 vaccines are widely credited for their role in reducing the spread, severity, and death caused by COVID-19.
The Moderna COVID‑19 vaccine, codenamed mRNA-1273 and sold under the brand name Spikevax, is a COVID-19 vaccine developed by American company Moderna, the United States National Institute of Allergy and Infectious Diseases (NIAID) and the Biomedical Advanced Research and Development Authority (BARDA). It is authorized for use in people aged twelve years and older in some jurisdictions and for people eighteen years and older in other jurisdictions to provide protection against COVID-19 which is caused by infection by the SARS-CoV-2 virus. It is designed to be administered as two or three 0.5 mL doses given by intramuscular injection at an interval of at least 28 days apart.
AD5-nCOV, trade-named Convidecia, is a single-dose viral vector vaccine for COVID-19 developed by CanSino Biologics. It conducted its Phase III trials in Argentina, Chile, Mexico, Pakistan, Russia, and Saudi Arabia with 40,000 participants.
CoronaVac, also known as the Sinovac COVID-19 vaccine, is an inactivated virus COVID-19 vaccine developed by the Chinese company Sinovac Biotech. It was Phase III clinical trialled in Brazil, Chile, Indonesia, the Philippines, and Turkey and relies on traditional technology similar to BBIBP-CorV and Covaxin, other inactivated-virus COVID-19 vaccines. CoronaVac does not need to be frozen and both the final product and the raw material for formulating CoronaVac can be transported refrigerated at 2–8 °C (36–46 °F), temperatures at which flu vaccines are kept.
Valneva COVID-19 vaccine, also known as the VLA2001 and VLA2101 , is a COVID-19 vaccine candidate developed by French biotechnology company Valneva SE in collaboration with American company Dynavax Technologies.
ZF2001, trade-named ZIFIVAX or ZF-UZ-VAC-2001, is an adjuvanted protein subunit COVID-19 vaccine developed by Anhui Zhifei Longcom in collaboration with the Institute of Microbiology at the Chinese Academy of Sciences. The vaccine candidate is in Phase III trials with 29,000 participants in China, Ecuador, Malaysia, Pakistan, and Uzbekistan.
EpiVacCorona is a peptide-based vaccine against COVID-19 developed by the VECTOR center of Virology. It consists of three chemically synthesized peptides that are conjugated to a large carrier protein. This protein is a fusion product of a viral nucleocapsid protein and a bacterial MBP protein. The third phase of a clinical trial, which should show whether the vaccine is able to protect people from COVID-19 or not, was launched in November 2020 with more than three thousand participants.
The CureVac COVID-19 vaccine was a COVID-19 vaccine candidate developed by CureVac N.V. and the Coalition for Epidemic Preparedness Innovations (CEPI). The vaccine showed inadequate results in its Phase III trials with only 47% efficacy.
SCB-2019 is a protein subunit COVID-19 vaccine developed by Clover Biopharmaceuticals using an adjuvant from Dynavax technologies. Positive results of Phase I trials for the vaccine were published in The Lancet and the vaccine completed enrollment of 29,000 participants in Phase II/III trials in July 2021. In September 2021, SCB-2019 announced Phase III results showing 67% efficacy against all cases of COVID-19 and 79% efficacy against all cases of the Delta variant. Additionally, the vaccine was 84% effective against moderate cases and 100% effective against hospitalization.
QazCovid-in, commercially known as QazVac, is a COVID-19 vaccine developed by the Research Institute for Biological Safety Problems in Kazakhstan. QazCoVac-P is a second COVID-19 vaccine developed by the Kazakh Biosafety Research Institute and in clinical trials.
Nanocovax is a Vietnamese COVID-19 vaccine candidate developed by Nanogen Pharmaceutical Biotechnology JSC. It is a subunit vaccine.
The Sinopharm WIBP COVID-19 vaccine, also known as WIBP-CorV, is one of two inactivated virus COVID-19 vaccines developed by Sinopharm. Peer-reviewed results show WIBP-CorV 72.8% effective against symptomatic cases and 100% against severe cases. The other inactivated virus COVID-19 vaccine developed by Sinopharm is BBIBP-CorV which is comparably more successful. 1 billion doses are expected to be produced per year.
UB-612 is a COVID-19 vaccine candidate developed by United Biomedical, Inc. Asia, Vaxxinity, and DASA. It is a peptide vaccine.
A viral vector vaccine is a vaccine that uses a viral vector to deliver genetic material coding for a desired antigen into the recipient's host cells. As of April 2021, six viral vector vaccines have been authorized for use in human at least one country: four COVID-19 vaccines and two Ebola vaccines.
NDV-HXP-S is a COVID-19 vaccine candidate developed by a team led by Jason McLellan at the University of Texas at Austin, together with groups from the Icahn School of Medicine at Mount Sinai and the National Institute of Allergy and Infectious Diseases Vaccine Research Center, based on an improved spike protein central to its resilience and efficacy.
Sputnik Light is a single dose COVID-19 vaccine developed by the Gamaleya Research Institute of Epidemiology and Microbiology. It consists of the first dose of the Sputnik V vaccine, which is based on the Ad26 vector, and it can be stored at a normal refrigerator temperature of 2–8 °C (36–46 °F). The institute says this version would be ideally suited for areas with acute outbreaks, allowing more people to be vaccinated quickly. It will also be used as a third (booster) dose for those who received Sputnik V at least 6 months earlier.
COVI-VAC is a COVID-19 vaccine being developed by Codagenix, Inc. It is currently in Phase I clinical trials, involving 48 participants which runs from December 2020 to June 2021.
COVID-19 vaccination in Thailand is an ongoing mass immunization in response to the ongoing pandemic in the country.
COVAX-19 is a recombinant protein-based COVID-19 vaccine developed by South Australian based biotech company Vaxine. It is under clinical trial in collaboration with the Iranian company CinnaGen.
ARCT-154, also known as VBC-COV19-154 in Vietnam, is a COVID-19 vaccine candidate developed by Arcturus Therapeutics. For its development, Arcturus collaborated with Vinbiocare, a Vietnamese company, for support with clinical trials and manufacturing.