The Pfizer and BioNTech mRNA vaccine for COVID-19 offered 95% safety with a passable security profile

Pfizer and BioNTech’s 2-dose BNT162b2 mRNA vaccine against coronavirus disease 2019 (COVID-19) provided 95% protection over a median of 2 months, according to results published in the New England Journal of Medicine.

Adults (N = 43,448) aged 16 and over were recruited for this study from July 2020 at 152 locations worldwide. 130 of these were in the USA, 9 in Turkey, 6 in Germany, 4 in South Africa, 2 in Brazil and 1 in Argentina.

In this ongoing multinational central efficacy study, researchers randomized participants in a 1: 1 ratio to receive 30 mg BNT162b2 doses 21 days apart (n = 21,720) or placebo (n = 21,728) intramuscularly. The primary endpoints were the vaccine’s effectiveness against laboratory-confirmed COVID-19 and safety, which was observed up to 6 months after the second dose. Adverse event data up to 14 weeks after the second dose are included in the report.

As of the reporting date, a total of 37,706 participants had a median of 2 months of safety data. These participants were 49% women, 83% white, 28% Hispanic American, 9% black, 35% were obese (BMI ³ 30.0 kg / m2) and 21% had at least 1 comorbid condition.

In patients with reactogenicity data (n = 8183), the data showed that vaccine recipients reported more local reactions than placebo. Mild to moderate pain at the injection site was commonly reported, and less than 1% reported severe pain. Patients older than 55 years reported less pain (first dose: 71%; second dose: 66%) than younger patients (first dose: 83%; second dose: 78%).

After the second dose, systematic reactogenicity was more common in younger vaccine recipients (fatigue 59%; headache 52%) than in older recipients (fatigue 51%; headache 39%). A similar pattern was observed in younger recipients (fatigue: 23%; headache 24%) and older recipients (fatigue: 17%; headache 14%) after the second placebo dose. Less than 2% of the participants reported severe systematic reactions.

Serious adverse events were similar in the vaccine and placebo groups (0.6% and 0.5%, respectively), including lymphadenopathy (64 vs 6), injury or condition that led to study discontinuation (4 vs 0), and death ( 2 vs 4). Investigators concluded that the deaths were unrelated to the study.

After the second dose, a total of 9 vaccine and 169 placebo recipients were diagnosed with COVID-19, which corresponds to an effectiveness of 94.6% (95% CI, 89.9% -97.3%). Between the first and second dose, 39 of the vaccine and 82 of the placebo recipients were diagnosed with COVID-19, which translates into 52% effectiveness (95% CI, 29.5% -68.4%).

This study was limited due to its sample size and associated time constraints. This study was able to detect adverse events with an incidence of 0.01%, but not for less common events. 14 weeks of follow-up data were only available for ~ 50% of participants, although follow-up continues for 2 years.

These results indicated that the BNT162b2 mRNA vaccine for COVID-19 was highly effective for 2 months with no evidence of serious adverse events in adults aged 16 years and over.

Disclosure: Several authors have stated that they are part of the pharmaceutical industry. For a full list of the details, see the original article.


Polack FP, Thomas SJ, Kitchin N. et al .; for the clinical trial group C4591001. Safety and effectiveness of the BNT162b2 mRNA Covid-19 vaccine. N Engl J Med. Published online December 31, 2020. doi: 10.1056 / NEJMoa2034577.

This article originally appeared on Infectious Disease Advisor

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