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COVID-19 vaccine clinical research

COVID-19 vaccine clinical research uses clinical research to establish the characteristics of COVID-19 vaccines. These characteristics include efficacy, effectiveness, and safety. As of November 2022, 40 vaccines are authorized by at least one national regulatory authority for public use:[1][2]

Further information: COVID-19 vaccine

As of June 2022, 353 vaccine candidates are in various stages of development, with 135 in clinical research, including 38 in phase I trials, 32 in phase I–II trials, 39 in phase III trials, and 9 in phase IV development.[1]

Formulation

A wide variety of technologies are being used to formulate vaccines against COVID-19. The development and deployment of mRNA vaccines and viral vector vaccines has been outstandingly rapid and can be described as revolutionary. However, global vaccine equity against COVID-19 has not been achieved. Conventional vaccine manufacturing approaches using whole inactivated virus (WIV), protein-based subunit vaccines, and virus-like particles (VLPs) may offer advantages in the development of vaccines for use in low- and middle-income countries (LMICs) and in addressing vaccine access gaps.[6]


Many vaccine candidates use adjuvants to enhance immunogenicity, as part of the delivery system or as an accompanying immune stimulant.[8][9] Vaccine adjuvant formulations using aluminum salts or "alum" may be particularly effective for technologies using inactivated COVID-19 virus and for recombinant protein-based or vector-based vaccines.[6][10]

Phase I trials test primarily for safety and preliminary dosing in healthy subjects. Dozens of subjects.

Phase II trials evaluate , dose levels (efficacy based on biomarkers) and adverse effects.[11][12] Hundreds of subjects. Sometimes Phase I and II trials are combined.[12]

immunogenicity

Phase III trials typically involve more participants at multiple sites, include a , and test effectiveness of the vaccine to prevent the disease (an "interventional" or "pivotal" trial), while monitoring for adverse effects at the selected dose.[11][12] Safety, efficacy, and clinical endpoints may vary, including the definition of side effects, infection or amount of transmission, and whether the vaccine prevents moderate or severe infection.[13][14][15]

control group

In Israel, among the 715,425 individuals vaccinated by the mRNA vaccines from 20 December 2020, to 28 January 2021, starting seven days after the second shot, only 317 people (0.04%) displayed mild/moderate COVID-19 symptoms and only 16 people (0.002%) were hospitalized.

[414]

CDC reported that under real-world conditions, mRNA vaccine effectiveness was 90% against infections regardless of symptom status; while effectiveness of partial immunization was 80%.

[415]

In the UK, 15,121 health care workers from 104 hospitals who had tested negative for antibodies prior to the study, were followed by twice a week from 7 December 2020 to 5 February 2021, a study compared the positive results for the 90.7% vaccinated share of their cohort with the 9.3% unvaccinated share, and found that the Pfizer-BioNTech vaccine reduced all infections (including asymptomatic), by 72% (58–86%) three weeks after the first dose and 86% (76–97%) one week after the second dose, while Alpha was dominant.[416]

RT-PCR tests

In Israel a study conducted from 17 January to 6 March 2021, found that Pfizer/BioNTech reduced asymptomatic Alpha infections by 94% and symptomatic COVID-19 infections by 97%.

[417]

A study on the Queensland Population having only ever been exposed to the Omicron strain of COVID-19 found vaccine effectiveness against symptomatic hospitalizations to be 70% in the general population and similar for First Nations peoples.

[418]

A study among pre-surgical patients across the system in the United States, showed that mRNA vaccines were 80% protective against asymptomatic infections.[419]

Mayo Clinic

A UK study found that a single dose of the is about 73% (27–90%) effective in people aged 70 and older.[420]

Oxford–AstraZeneca COVID-19 vaccine

A study finds that nearly all teenagers admitted to intensive care units because of COVID-19 were unvaccinated.

[421]

Side effects

All vaccines, including COVID-19 ones, can have minor side effects related to the mild trauma associated with the introduction of a foreign substance into the body.[483][484] 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.[485]


Serious adverse events that follow the administration of vaccines are of high interest to the public.[486] It is important to recognize that the occurrence of an adverse event following vaccination does not necessarily mean that the vaccine caused the adverse event; the health problem may have been unrelated. Reporting of all adverse events, careful followup and statistical analysis of occurrences are required to determine whether or not a specific health problem is more likely to occur after a vaccine is administered.[487][488][489]


More serious side effects are very rare. Before COVID-19 vaccines such as Moderna and Pfizer/BioNTech were authorized for use in the general population, they had to pass phase III studies involving tens of thousands of people. Any serious side effects that did not appear during that testing are likely to occur less often than ~1 in 10,000 cases. It is important that Phase III trials be diverse, to ensure that safety results apply broadly. It is possible that side effects may affect a population that was not adequately represented during the initial testing. Pregnant women, immunocompromised people, and children are usually excluded from initial studies because they may be at higher risk. Further studies may be done to ensure their safety before vaccines are authorized for use in such populations. Subsequent examinations of the use of COVID vaccines in pregnant people and in children have shown similar outcomes to the general population and do not suggest greater risk for these groups.[489]