PFE Pfizer Inc

By Jared S. Hopkins 

The Covid-19 vaccine from Pfizer Inc. and BioNTech SE is highly effective at protecting against symptomatic Covid-19 up to six months after the second dose, the companies said.

The findings, released Thursday, emerged from a continuing review of how volunteers in the shot's late-stage trial were faring.

The further analysis suggested the vaccine worked effectively against a variant first identified in South Africa, Pfizer and BioNTech said. And the companies said they haven't found serious safety concerns so far.

"It is an important step to further confirm the strong efficacy and good safety data we have seen so far, especially in a longer-term follow-up," said BioNTech Chief Executive Ugur Sahin.

Pfizer Chief Executive Albert Bourla said the additional results provide "further confidence in our vaccine's overall effectiveness."

The vaccine was the first authorized in the West last year, after the late-stage, or Phase 3, trial found it was 95% effective at preventing Covid-19 with symptoms and was generally safe.

In the U.S., the vaccine is cleared for use in people age 16 and older.

The shot has now become a key cog in global vaccination efforts. The companies have distributed more than 200 million doses globally and plan to produce 2.5 billion doses this year.

On Wednesday, the companies said the vaccine was 100% effective in children ages 12 to 15, results that could lead to the vaccine's U.S. authorization for use in adolescents in May.

The vaccine uses a new gene-based technology, named messenger RNA after the molecules that carry genetic instructions to cells to make proteins. Production of the proteins trains the immune system to recognize the coronavirus and fight it.

The new analysis looked at the vaccine's performance in 46,307 people who enrolled in the Phase 3 trial, starting in July.

Of the 927 cases of symptomatic Covid-19 observed through March 13, 850 were in people who received a placebo and 77 in people who were vaccinated, according to the companies.

That corresponds to a vaccine efficacy of 91.3% up to six months after getting the second dose, Pfizer and BioNTech said.

The protection remained generally consistent across age, gender, race and ethnicity, as well as among individuals with underlying health conditions, the companies said.

The vaccine was also 95% to 100% effective against severe disease, with the precise figure depending on whether researchers used a definition of severe disease from the U.S. Centers for Disease Control and Prevention or one from the U.S. Food and Drug Administration.

Some 800 trial subjects were enrolled in South Africa, where a more contagious variant of the virus was first identified. Among those volunteers, there were nine cases of Covid-19, all in people who got a placebo.

The findings, the companies said, support earlier analyses that have shown the vaccine generated a slightly lower immune response against the variant than the more common strain circulating in the U.S., but was still effective at neutralizing the variant virus.

Of the 697 cases of symptomatic Covid-19 among study subjects in the U.S., 647 were in people who received a placebo, with the rest in vaccinated subjects, indicating 92.6% efficacy, according to the companies.

The companies plan to continue to monitor study subjects for two years.

Write to Jared S. Hopkins at jared.hopkins@wsj.com

(END) Dow Jones Newswires

April 01, 2021 06:59 ET (10:59 GMT)

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