The ongoing Phase 3 clinical trial of the Pfizer / BioNTech coronavirus vaccine confirms that its protection lasts at least six months after the second dose, the companies said on Thursday.
It is the first analysis of how long protection for a coronavirus vaccine lasts and, although six months is a modest target, it is more than the 90 days of protection that is the best estimate offered so far.
The vaccine remains more than 91% effective against diseases with any symptoms for six months, the companies said. And it appeared to be fully effective against the worrying variant B.1.351 of the virus, which is the dominant strain that circulates in South Africa and that researchers feared had evolved to escape protection from vaccines.
“The vaccine was 100% effective against serious illnesses, as defined by the US Centers for Disease Control and Prevention (CDC), and 95.3% effective against severe cases of Covid-19, as defined by the US Food and Drug Administration ( FDA), “BioNTech said in a joint statement.
On Wednesday, the companies said that a small trial with volunteers aged 12 to 15 years showed 100% effectiveness in this age group.
“This data confirms the favorable efficacy and safety profile of our vaccine and positions us to submit an application for a biological license to the U.S. FDA,” said Albert Bourla, Pfizer president and chief executive officer, in a statement. A BLA is a request for full approval. The vaccine is currently authorized for emergency use, USA, which is not fully approved.
“The high effectiveness of the vaccine seen within six months after a second dose and against the variant prevalent in South Africa provides more confidence in the overall effectiveness of our vaccine.” The company has studied the vaccine in more than 46,000 volunteers and observed 927 cases Covid-19 confirmed.
“Of the 927 confirmed symptomatic cases of Covid-19 in the trial, 850 cases of Covid-19 were in the placebo group and 77 cases in the BNT162b2 group, corresponding to a vaccine effectiveness of 91.3%,” he said.
“Thirty-two cases of severe disease, as defined by the CDC, were observed in the placebo group versus none in the group vaccinated with BNT162b2, indicating that the vaccine was 100% effective in this analysis against severe disease by defining the CDC. One case, as defined by the FDA, it was observed in the placebo group versus one case in the group vaccinated with BNT162b2, indicating 95.3% effectiveness according to the FDA definition.
“These definitions are important. The FDA’s definition of serious illness included high respiratory rate, indicating breathing difficulty; high heart rate, oxygen saturation level of 93% or less; respiratory insufficiency severe enough to require oxygen or additional ventilation; drop in blood pressure indicating shock, significant renal, hepatic or neurological dysfunction, admission to an intensive care unit or death.
The CDC definition includes a blood oxygen level of 94% or less and an X-ray finding of pulmonary infiltrates – an indication of pneumonia – greater than 50%
The most common adverse events were pain at the injection site, fatigue and headache. “In South Africa, where the B.1.351 strain is prevalent and 800 participants were enrolled, nine cases of Covid-19 were observed, all in the group of the placebo, indicating 100% vaccine efficacy, “said the company.
“The safety of the vaccine has been assessed in more than 44,000 participants aged 16 and over, with more than 12,000 vaccinated participants with at least six months of follow-up after the second dose.”
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