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Our team has reviewed 14 papers on #COVID vaccine phase 1-3 trials, including those produced by @moderna_tx, @BioNTech_Group/ @pfizer,& @OxfordVacGroup/ @AstraZeneca. All results to date have shown that the vaccines are safe and have very few side effects, including in older adults
Phase 1 trials focus on safety & finding the appropriate dose. Phase 2 trials study safety & immune response. Phase 3 trials also investigate safety & test vaccine efficacy. One key is that all 3 phases examine safety & build on each other to guarantee the safest vaccine possible
Moderna and Pfizer both produced an mRNA vaccine. While this is a newer type of vaccine that many are not familiar with, there is evidence of long-term safety of other mRNA vaccines (see @nature article). Oxford/AstraZeneca made an adenovirus-based vaccine
https://www.nature.com/articles/nrd.2017.243/tables/2
https://www.nature.com/articles/nrd.2017.243/tables/2
In phase 1 trials of the Moderna vaccine, 45 adults age 18-55 received two doses 28 days apart. Side effects, including fatigue, chills, headache, myalgia, and pain at injection site, were mild and more common after the second dose.
https://ncrc.jhsph.edu/research/an-mrna-vaccine-against-sars-cov-2-preliminary-report/
https://ncrc.jhsph.edu/research/an-mrna-vaccine-against-sars-cov-2-preliminary-report/
Moderna also had a separate phase 1 trial in older adults (age 56-70 and 71+). Similar to the trial in adults age 18-55, older adults experienced mild adverse events, which were more common after the second dose. https://ncrc.jhsph.edu/research/safety-and-immunogenicity-of-sars-cov-2-mrna-1273-vaccine-in-older-adults/
In the Pfizer phase 1/2 trials, 45 adults (age 18-55) were given two doses 21 days apart. Half of participants reported mild adverse events, including pain at the injection site, fatigue, headache, and fever, but no adverse events were considered severe. https://ncrc.jhsph.edu/research/phase-1-2-study-of-covid-19-rna-vaccine-bnt162b1-in-adults/
Older participants (age 65-85) in the Pfizer trial also reported mild-to-moderate pain at the infection site and mild systemic events including headache and fatigue. A few people reported fever. https://ncrc.jhsph.edu/research/safety-and-immunogenicity-of-two-rna-based-covid-19-vaccine-candidates/
Among 43,548 participants in Pfizer's phase 2/3 trial, serious adverse events were rare in both the vaccine and placebo groups (0.6% and 0.5%). Most common adverse reactions were mild-to-moderate pain, swelling at the injection site, fatigue, and headache https://ncrc.jhsph.edu/research/safety-and-efficacy-of-the-bnt162b2-mrna-covid-19-vaccine/
In Oxford/AstraZeneca's phase 1/2 trial, 1077 adults aged 18-55 were randomized to vaccine or placebo arms. Adverse events (including pain, fever, muscle ache, headache, and malaise) were mostly mild or moderate and were more common in the vaccine group. https://ncrc.jhsph.edu/research/safety-and-immunogenicity-of-the-chadox1-ncov-19-vaccine-against-sars-cov-2-a-preliminary-report-of-a-phase-1-2-single-blind-randomised-controlled-trial/
Among 560 participants in the phase 2 trial, there were no serious adverse events related to the vaccine. Participants reported fatigue, headache, muscle pain, and pain at injection site. The vaccine was well tolerated in adults older than 55 years. https://ncrc.jhsph.edu/research/safety-and-immunogenicity-of-chadox1-ncov-19-vaccine-administered-in-a-prime-boost-regimen-in-young-and-old-adults-cov002-a-single-blind-randomised-controlled-phase-2-3-trial/
Among 11,636 adults in phase 3 trials, the incidence of severe adverse events was similar between those receiving the Oxford/AstraZeneca vaccine and placebo. Only 3 adverse events were deemed to be possibly related to the vaccine or placebo inoculations https://ncrc.jhsph.edu/research/safety-and-efficacy-of-the-chadox1-ncov-19-vaccine-azd1222-against-sars-cov-2-an-interim-analysis-of-four-randomised-controlled-trials-in-brazil-south-africa-and-the-uk/
Many have voiced concerns about potential safety issues because the trials appear to have been done fast. It’s critical to note technologies used in these trials existed pre-COVID and have been studied for years (even mRNA vaccine technologies; see linked @nature review above)
Unprecedented levels of funding and redirected effort also allowed for larger study enrollment. Having more participants reduces the time needed to observe whether there is a difference in outcomes between vaccine and placebo arms
Each of the vaccines described above went through the typical regulatory hurdles and produced the necessary data required for public rollout. As with any vaccine, ongoing surveillance of vaccine safety and effectiveness is needed after widespread rollout.
Summary: Trials for the three leading #COVID19 vaccines all suggest that these vaccines are very safe. Side effects are uncommon and generally mild. Early efficacy data is also very promising. We will continue to review results as they become available.
