Study on aggressive strain of Covid-19 in Brazil suggests limits of Chinese vaccine

Researchers in Brazil, the UK and the US have found that plasma from eight people vaccinated five months ago with CoronaVac “failed to effectively neutralize” the new Amazon strain, called P.1. The study did not show whether CoronaVac could still prevent people from getting sick from the variant, one of the main goals of vaccination campaigns.

While the study sample size was small and requires further testing, the fact that all eight samples produced the same result is a “notable phenomenon”, suggesting that CoronaVac is less able to thwart P infections. .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-backed broadcaster CGTN that Sinovac published this week, CEO Yin Weidong said that, if necessary, it would take less time to develop a vaccine for the variants than to start from scratch.

“It’s like there’s this thief we’ve already caught,” he says. “Even though it is mutating, we can fully use the current research and production capacity to effectively develop a vaccine for the new variant.”

Mr Weidong said in the interview that Sinovac found that a person’s antibodies dropped six months after vaccination with CoronaVac, adding that the company was still researching the length of protection and would release the data soon. He said the company is also reviewing the effectiveness of offering additional booster shots.

As the P.1 strain has spread rapidly in Brazil and more than 20 other countries, concerns have grown over the effectiveness of existing Covid-19 vaccines against the variant and the many others emerging in the greater Latin American countries.

CoronaVac, which is expected to be rolled out across much of Latin America and other developing countries in Africa and Asia, is Brazil’s best hope of beating the pandemic in the short term, experts said. public health.

The disease has killed more than 260,000 people in Brazil. As other countries around the world have put the worst of the pandemic behind them, public health experts say Brazil faces its darkest days yet, with its daily toll expected to exceed that of states. -United and reach a new high in the coming weeks.

“This will be the greatest humanitarian tragedy in Brazilian history,” warned Edinho Silva, the mayor of Araraquara, a hard-hit city in the state of São Paulo, this week. A recent study showed that over 90% of Covid-19 patients in crowded Araraquara hospitals tested positive for the P.1 strain.

The variant, which first appeared in the Amazon city of Manaus late last year, is 1.4-2.2 times more contagious than versions of the virus previously found in Brazil, and 25% in 61% more able to re-infect people, according to a recent study.

Its effects are already being felt across the country. Hospitals in most states are already running out of intensive care beds or are operating near full capacity, while oxygen shortages have recently led to the deaths of many suffocating patients in the Amazon. Prosecutors have investigated reports that intubated patients in the area were tied to their beds following a shortage of sedatives.

Public health specialists have said Brazil now faces a race against time to vaccinate its population before other new, potentially aggressive variants of Covid-19 emerge. Researchers estimate that there are already hundreds of strains of the disease circulating in the country, although P.1 is widely regarded as the most worrying.

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

Despite an efficacy rate of around 50%, one of the lowest rates of any existing Covid-19 vaccine, CoronaVac has prevented 100% of moderate and severe cases of the disease, stage clinical trials have shown. advanced in Brazil.

The P.1 study published on March 1, which also drew on researchers from the University of Oxford and the Washington University School of Medicine, provides the first insight into how CoronaVac may respond to P.1.

However, infectious disease specialists, including the study’s authors, have warned that more, larger studies should be done to show how well CoronaVac works against the newer variants and whether it can still prevent people to fall ill with P.1.

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

“This is an exploratory study, a flashing yellow light, but not a red light,” said Carlos Fortaleza, an epidemiologist at São Paulo State University, who was not involved in the study. “The preliminary results must be published with great care,” he said.

Some scientists fear that such studies will deter people from getting vaccinated with CoronaVac, which has been heavily criticized by the president himself.

Bolsonaro, a fierce critic of China, told his supporters late last year that CoronaVac could cause them to die or suffer disabilities, without providing any evidence. Rather, he has championed hydroxychloroquine, an antimalarial drug, and more recently the use of an experimental nasal spray to treat patients with Covid-19.

Public health experts have widely blamed Mr Bolsonaro’s administration for the growing death toll in the country. While many state governors have placed restrictions on keeping Brazilians in their homes, the president has encouraged people to break those rules and rallied around face masks.

“Stop complaining and whining,” Bolsonaro, a fiery former army captain, said this week in what some experts also said was an attempt to divert press attention from a scandal of growing corruption involving his son. “How long are you going to keep crying about this?”

—Chao Deng in Taipei contributed to this article.

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