How much does Pfizer effectiveness decline over time?

Embargoed until: Publicly released: 2021-10-07 08:00

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Six months after Pfizer vaccination, the effectiveness of the vaccine is lower than its peak but it is still highly effective at keeping people out of hospital, according to international research. A study estimated the effectiveness of the vaccine in people in Qatar from January to September, 2021 using reported cases of COVID-19 and severe to fatal cases. They found around six months after vaccination, effectiveness at preventing all infections had declined to 20 per cent, but effectiveness against severe, critical and fatal COVID-19 had remained at 96 per cent. In a second study in Israel, researchers tested the antibodies of vaccinated health care workers over six months. They say immunoglobin G antibodies decreased at a steady rate over that time, while neutralising antibody levels decreased rapidly over the first three months before the decline slowed.