Pfizer/BioNTech Vaccine Shows High Efficacy After Six Months
The current study took place in over 150 locations worldwide and included over 45,000 healthy and individuals with stable chronic illnesses. None of the participants had a history of Coronavirus infection, though testing could reveal asymptomatic infection in the past or present.
The Pfizer/BioNTech BNT162b2 vaccine appears to be very effective and safe in protecting against SARS-CoV-2 infection.
All the participants were given two intramuscular vaccine doses or a placebo with a 21-day interval.
The vaccine’s effectiveness was determined by checking for lab-confirmed SARS-CoV-2 at least seven days following the second vaccine. Scientists measured the incidence separately in people who had previously been infected and those who had never been infected.
They also discovered severe SARS-CoV-2 and viral lineages in people who had never been infected before. More than 50% of the individuals were observed for six months or longer.
The study found that about 10,000 people experienced adverse reactions, with around 360 of them having already been infected. Some of the reactions related to the infection included mild or even moderate pain at the injection site.
Poor appetite, lethargy, weakness, and fatigue are some of the AEs (adverse events) that the vaccine could cause. However, major AEs were uncommon, and there were no new cases after the initial report. In neither group, there were no deaths attributed to or connected to the immunization.
The study revealed the vaccine protects people aged 12 and up, reducing the risk of severe disease by 97% and infection by 91%. This protection starts somewhere about the 11th day following the first vaccine, offering 92% protection until the individual receives the second dose.
Scientists detected a 6% drop in efficacy two months after the second dose—from 97% to 84%.
Scientists are planning a two-year follow-up to determine if this decline will persist and, if so, whether a third booster would be required. This experimental observation will be supplemented by real-world data.
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