#Covid vaccine side effect trial#

Individuals with known past SARS-CoV-2 infection were more likely to have adverse effects after the first dose than were those without known past infection. Headache and fatigue were more common in women than in men, in people aged 55 years or younger than in people older than 55 years, and after the second than after the first dose. Reported side-effects were minor in severity and of short duration. In this large prospective observational study, we assessed adverse effects from the two COVID-19 vaccines in use in the UK at the time of writing (BNT162b2 and ChAdOx1 nCoV-19), as well as self-reported infection rates following one dose or two doses of BNT162b2 and one dose of ChAdOx1 nCoV-19. No study investigated the prevalence of adverse effects of the vaccines and all studies reported both vaccines to be highly effective. Besides the original phase 1–3 trials, we found one published article and two preprints on data from Israel investigating the effectiveness of the Pfizer-BioNTech vaccine (BNT162b2), a preprint from the UK exploring the effectiveness of both the BNT162b2 and Oxford-AstraZeneca (ChAdOx1 nCoV-19) vaccines in individuals aged 70 years or older in the community, and a study that linked health records for all vaccinated people in Scotland to investigate COVID-19 hospitalisation and mortality after vaccination. We did not restrict our search by language or type of publication. We searched PubMed for articles published up to March 10, 2021, using the terms (“BNT162b2“ OR “mRNA Covid-19 Vaccine” OR “ChAdOx1 nCoV-19” OR “adenovirus-vectored Covid-19 vaccine”) AND (“effectiveness” OR “reinfection” OR “side-effects” OR “adverse effects” OR “reactogenicity” OR “phase IV”).

#Covid vaccine side effect trial#

5 The ChAdOx1 nCoV-19 trial found efficacy against symptomatic disease of 76% at 22–90 days after at least one standard dose.

3 The effectiveness of this vaccine in reducing infection, severe disease, hospitalisation, and death with COVID-19 has been reported for the whole of Israel, 4 with reanalysis of the data from Israel revealing it to be 90% effective 2 weeks after the first dose. Phase 3 trials reported the BNT162b2 vaccine to have an efficacy of 52% at 12 days after the first dose and of 95% after the second dose if administered 3–4 weeks apart in participants without previous SARS-CoV-2 infection. 1 In late December, 2020, based on advice from the Joint Committee on Vaccination and Immunisation, 2 the UK Government decided to delay the administration of second doses. The first two vaccines have been rolled out across the UK since Dec 8, 2020, and Jan 4, 2021, respectively. The UK's Medicines and Healthcare products Regulatory Agency has given emergency use authorisation to three COVID-19 vaccines: the Pfizer-BioNTech mRNA vaccine (BNT162b2), the Oxford-AstraZeneca adenovirus-vectored vaccine (ChAdOx1 nCoV-19), and the Moderna mRNA vaccine (mRNA-1273).

Significant reductions in infection risk were seen starting at 12 days after the first dose, reaching 60% (95% CI 49–68) for ChAdOx1 nCoV-19 and 69% (66–72) for BNT162b2 at 21–44 days and 72% (63–79) for BNT162b2 after 45–59 days. 3106 of 103 622 vaccinated individuals and 50 340 of 464 356 unvaccinated controls tested positive for SARS-CoV-2 infection. Local effects were similarly higher in individuals previously infected than in those without known past infection (1♴ times after the first dose of ChAdOx1 nCoV-19 and 1♲ times after the first dose of BNT162b2). Systemic side-effects were more common (1♶ times after the first dose of ChAdOx1 nCoV-19 and 2♹ times after the first dose of BNT162b2) among individuals with previous SARS-CoV-2 infection than among those without known past infection. Local side-effects were reported by 71♹% (150 023 of 208 767) of individuals after the first dose of BNT162b2, by 68♵% (9025 of 13 179) after the second dose of BNT162b2, and by 58♷% (104 282 of 177 655) after the first dose of ChAdOx1 nCoV-19. Systemic side-effects were reported by 13♵% (38 155 of 282 103) of individuals after the first dose of BNT162b2, by 22♰% (6216 of 28 207) after the second dose of BNT162b2, and by 33♷% (116 473 of 345 280) after the first dose of ChAdOx1 nCoV-19. Between Dec 8, and March 10, 2021, 627 383 individuals reported being vaccinated with 655 590 doses: 282 103 received one dose of BNT162b2, of whom 28 207 received a second dose, and 345 280 received one dose of ChAdOx1 nCoV-19.