The Novavax vaccine is 89% effective against Covid-19 in the UK study

However, the vaccine was less effective in a separate, mid-range study in South Africa, where another variant has spread. In South Africa, Novavax shot was approximately 49.4% effective against Covid-19 in the study. Preliminary results showed that over 90% of the sick subjects for whom sequencing data were available were infected with the new variant circulating in South Africa.

Given the lower efficacy in South Africa, Novavax said it has begun work on a modified version of its vaccine that better targets the strain first identified there and plans to start testing in the second quarter.

Overall, however, the positive performance indicates another vaccine that will soon join the arsenal of photographs available in some countries, while health authorities are struggling with limited supplies while competing to inoculate residents.

“We now have a vaccine, the first vaccine that has proven effective not only in the original Covid-19 strain prototype, but in two strains, one in the UK, one in South Africa,” said Stanley Erck, executive director of Novavax, in an interview. “These are the only data that show that we can achieve effectiveness against all three.”

In the UK study, Novavax said that based on tests performed on 56 of the 62 cases of Covid-19, the vaccine appeared to be 95.6% effective against the original Covid-19 strain and 85.6% against the strain of Covid-19. UK.

Novavax, which has never brought a vaccine to market, published the results of the study in a press release. The data were not subject to standard verification by external experts prior to publication in a medical journal.

Gaithersburg, Maryland, said it has begun the process of requiring UK health regulators to clearly use the company’s vaccine in the country.

Novavax said it would provide the new data to US regulators, which could lead to an authorization by April. But US regulators may not decide on the vaccine until they see the results of a third, ongoing, late-stage fire test in the US and Mexico.

The study enrolled 16,000 people, to a target of 30,000, and Novavax said the initial results may reach the end of March.

Vaccines from Pfizer Inc.

and its partner BioNTech SE,

as well as from Moderna Inc.,

have been licensed for use in the US, while a photo from AstraZeneca PLC and Oxford University is licensed in the UK

Novavax has one of the most advanced vaccines in development. So is Johnson & Johnson,

which is expected to release the results of the late-stage or phase 3 studies for its vaccine by next week.

The vaccination mechanism has gained new urgency from the emergence of strains in the UK and South Africa, as well as Brazil, threatening to spread faster than the old version of the virus and evade some treatments.

Researchers have also tried to see how well they will protect vaccines against new variants and whether Covid-19 drugs will continue to work.

Moderna Inc. said this week that it would develop a booster after lab tests showed its Covid-19 vaccine had a less neutralizing effect against the variant circulating in South Africa.

Moderna and Pfizer said laboratory tests suggest that their vaccines would still be effective against variants identified in the UK and South Africa. Both variants were detected in the USA, as well as the one identified in Brazil.

The Novavax vaccine contains spike-like proteins found on the surface of the coronavirus.

The researchers designed the tip-like proteins delivered by the shot to trigger an immune response that can later defend against the real coronavirus if a vaccinated person is exposed to it.

Novavax produces proteins in insect cells. The vaccine also contains an adjuvant, designed to boost the immune responses generated by the vaccine, derived from the bark of an evergreen tree native to Chile.

The protein-adjuvant combination is generally similar to the design of vaccines against other diseases, such as the latest shingles shot from GlaxoSmithKline PLC.

Novavax began the UK Phase 3 Essential Study in September and enrolled approximately 15,000 people.

The study looked at whether adults who were given two doses of the vaccine, three weeks apart, had mild to severe Covid-19 at a lower rate than placebo-treated subjects starting one week after placebo. second dose.

Pfizer-BioNTech and Moderna vaccines were over 94% effective in phase 3 studies, while the AstraZeneca vaccine was 62% effective in many of the subjects studied.

Novavax said there were “low levels” of severe side effects, which were balanced between those who received the vaccine and those who received a placebo in the UK study.

In the smallest phase 2 study in South Africa, Novavax compared its vaccine with a placebo in about 4,400 people. This study also included a subgroup of people who were HIV-positive.

Excluding results from people who are HIV-positive, the vaccine was about 60 percent effective, Novavax said.

Health experts believe that the flu vaccine works well if it is 60% effective, although other vaccines can be 90% effective. The US Food and Drug Administration has stated that Covid-19 vaccines should be at least 50% effective.

The Novavax Phase 3 study of the vaccine in the US and Mexico began in late December. The start of the process was delayed because Novavax was facing some manufacturing issues.

It was the first protein-based Covid-19 vaccine to be widely tested in the United States.

The federal government agreed in July last year to provide $ 1.6 billion to Novavax to help fund testing and manufacturing its vaccine preparations and purchase 100 million doses.

In August, the British government agreed to buy 60 million doses of Novavax vaccine and work with the company on the phase 3 study.

Last year, Novavax said that in a small, early-stage study of healthy volunteers, its vaccine generated promising immune responses and was generally well tolerated.

If authorized for use, the vaccine could generate sales of $ 3.45 billion this year, according to the average estimate of analysts surveyed by FactSet.

—Gregory Zuckerman contributed to this article.

Write to Peter Loftus at [email protected]