Research on aggressive Covid-19 strain in Brazil suggests limitations of the Chinese vaccine

Researchers from Brazil, the UK and the US found that plasma from eight people vaccinated with CoronaVac five months ago ‘did not neutralize efficiently’ the new Amazonian strain called P.1. The study did not show whether CoronaVac can still prevent people from getting sick from the variant, one of the main goals of vaccination campaigns.

Although the sample size of the study was small and needs further testing, the fact that all eight samples gave the same result is a ‘remarkable phenomenon’, suggesting that CoronaVac is less able to thwart infections of P.1 than versions of the virus previously found in Brazil, said William de Souza, of the University of São Paulo in Ribeirão Prêto, one of the study’s authors.

Sinovac, the Chinese company that produces CoronaVac, did not respond to requests for comment. In an interview with state-sponsored broadcaster CGTN that Sinovac released this week, Chief Executive Officer Yin Weidong said it would take less time to develop a vaccine for the variants if necessary than it would take from scratch.

“It’s like there’s a thief we’ve already caught,” he said. “Even if it mutates, we can fully use the current research and manufacturing capacity to effectively develop a vaccine for the new variant.”

Mr. Weidong said in the interview that Sinovac had discovered that a person’s antibodies had declined six months after being vaccinated with CoronaVac, adding that the company was still investigating how long the protection would last and this data would soon release. He said the company is also investigating the effectiveness of offering additional booster shots.

As the P.1 strain has spread rapidly across Brazil and more than 20 other countries, concerns have grown about how well existing Covid-19 vaccines will work against the variant and the many others that are in Latin America’s largest country. America popping up.

CoronaVac, which is expected to roll out across much of Latin America and other developing countries in Africa and Asia, is Brazil’s best hope for overcoming the pandemic in the near term, public health specialists said.

The disease has killed more than 260,000 people in Brazil. While other countries around the world have left the worst of the pandemic behind, public health experts say Brazil is experiencing its darkest days ever, with a daily death toll that will surpass that of the US and hit another peak in the coming weeks.

“This will be the greatest humanitarian tragedy in Brazil’s history,” Edinho Silva, the mayor of Araraquara, a badly affected city in São Paulo state, warned this week. A recent study found that more than 90% of Covid-19 patients in full Araraquara hospitals tested positive for the P.1 strain.

The variant, which first showed up in the Amazon city of Manaus at the end of last year, is 1.4 to 2.2 times more contagious than versions of the virus previously found in Brazil, and 25% to 61% more capable. to re-infect humans, according to a recent study. .

Its effects are already being felt across the country. Hospitals in most states are either already out of IC beds or operating at near full capacity, while oxygen shortages have recently resulted in dozens of patients in the Amazon asphyxiated. Prosecutors have investigated reports that intubated patients in the region were bedridden after a shortage of sedatives.

According to public health specialists, Brazil is now in a race against time to vaccinate its population before other potentially aggressive new Covid-19 variants emerge. Researchers estimate that hundreds of types of the disease are already circulating in the country, although P.1 is widely believed to be the most troubling.

After President Jair Bolsonaro spent months last year downplaying the pandemic and negotiating a vaccine supply deal with Pfizer Inc. To screw up, the country has relied largely on CoronaVac since launching its vaccination campaign in January. The Chinese vaccine, developed in collaboration with the State of São Paulo, accounts for more than 70% of the Covid-19 injections administered in Brazil.

Despite an efficacy rate of about 50%, one of the lowest rates for any existing Covid-19 vaccine, CoronaVac was able to prevent 100% of moderate and severe cases of the disease, late-stage clinical trials in Brazil found.

The P.1 study published March 1, which also relied on researchers at the University of Oxford and Washington University School of Medicine, provides the first indications of how CoronaVac might respond to P.1.

However, infectious disease experts, including the study authors, have warned that other broader studies would be needed to show how well CoronaVac works against new variants and whether it can still prevent people from getting sick with P. 1.

The study itself was not intended to test CoronaVac specifically, but to test how antibodies created by vaccination or previous infections from other versions of Covid-19 react when confronted with the new P.1 strain.

“It’s an exploratory study, a blinking yellow light, but not a red,” said Carlos Fortaleza, an epidemiologist at São Paulo State University who was not involved in the study. “Preliminary results must be released with great care,” he said.

Some scientists have expressed concern that such studies could deter people from getting vaccinated with CoronaVac, which has been heavily criticized by the president himself.

Bolsonaro, a fierce China critic, told his supporters late last year that CoronaVac could cause them to die or become disabled without providing any evidence. He has instead championed the anti-malarial drug hydroxychloroquine, and more recently the use of an experimental nasal spray to treat Covid-19 patients.

Public health specialists have largely blamed Mr Bolsonaro’s government for the rising death toll in the country. While many state governors have imposed restrictions on keeping Brazilians at home, the president has encouraged people to break those rules and has campaigned against face masks.

“Stop whining and whining,” said Mr. Bolsonaro, an ardent former army captain, this week. According to some experts, it was also an attempt to divert press attention from a growing corruption scandal involving his son. “How long do you keep crying about it?”

—Chao Deng in Taipei contributed to this article.

Write to Samantha Pearson at [email protected] and Luciana Magalhaes at [email protected]