Virus World

Moderna Inc (MRNA.O) said on Wednesday early human trial data shows that a third dose of either its current COVID-19 shot or an experimental new vaccine candidate increases immunity against variants of COVID-19 first found in Brazil and South Africa.  The booster shots, given to volunteers previously inoculated with Moderna's two-dose vaccine regimen, also boosted antibodies against the original version of COVID-19, Moderna said. The early data comes from a 40-person trial testing both Moderna's existing shot and a version developed to protect against the South African variant of COVID-19 called mRNA-1273.351. Moderna is also studying a shot that combines both the new and existing vaccine. The results show that while booster shots of either version of the vaccine increased antibodies against all of the variants of COVID-19 tested in the trial, the new booster had a bigger response against the South African variant than the original vaccine.

"We are encouraged by these new data, which reinforce our confidence that our booster strategy should be protective" against the newer variants of COVID-19, Stephane Bancel, Moderna's chief executive officer, said in a statement. Both booster shots were well tolerated, with side effects similar to what volunteers in previous studies experienced from the second dose of its vaccine, Moderna said. The new variants of COVID-19 first discovered in South Africa and Brazil are thought to be more resistant to existing vaccines. Both variants have been detected in the United States but comprise only a small fraction of U.S. cases so far, according to federal data last updated in April. Moderna’s study is looking at levels of antibodies in participants’ blood that combat COVID-19, an early indication that they will be protected against the virus. It first announced it was studying ways to protect against the variants of COVID-19 in February.  Moderna expects to share additional data soon on another potential booster shot that mixes its existing COVID-19 vaccine with the newly developed shot. The U.S. government scientists at the National Institute of Allergy and Infectious Diseases (NIAID) is conducting a separate early stage study of mRNA-1273.351, Moderna said.

Moderna's Press Release (May 5, 2021):

https://investors.modernatx.com/news-releases/news-release-details/moderna-announces-positive-initial-booster-data-against-sars-cov 

The COVID-19 vaccine from Pfizer Inc and BioNTech SE was able to neutralize a new variant of the coronavirus spreading rapidly in Brazil, according to a laboratory study published in the New England Journal of Medicine on Monday. Blood taken from people who had been given the vaccine neutralized an engineered version of the virus that contained the same mutations carried on the spike portion of the highly contagious P.1 variant first identified in Brazil, the study conducted by scientists from the companies and the University of Texas Medical Branch found.  The scientists said the neutralizing ability was roughly equivalent the vaccine’s effect on a previous less contagious version of the virus from last year. The spike, used by the virus to enter human cells, is the primary target of many COVID-19 vaccines.

In previously published studies, Pfizer had found that its vaccine neutralized other more contagious variants first identified in the United Kingdom and South Africa, although the South African variant may reduce protective antibodies elicited by the vaccine. Pfizer has said it believes its current vaccine is highly likely to still protect against the South African variant. However, the drugmaker is planning to test a third booster dose of their vaccine as well as a version retooled specifically to combat the variant in order to better understand the immune response.

Original Study Published in N.Eng. J. Medicine (March 8, 2021):

https://doi.org/10.1056/NEJMc2102017

Brazil's P1 coronavirus variant, behind a deadly COVID-19 surge in the Latin American country that has raised international alarm, is mutating in ways that could make it better able to evade antibodies, according to scientists studying the virus.  Research conducted by the public health institute Fiocruz into the variants circulating in Brazil found mutations in the spike region of the virus that is used to enter and infect cells. Those changes, the scientists said, could make the virus more resistant to vaccines - which target the spike protein - with potentially grave implications for the severity of the outbreak in Latin America’s most populous nation. “We believe it’s another escape mechanism the virus is creating to evade the response of antibodies,” said Felipe Naveca, one of the authors of the study and part of Fiocruz in the Amazon city of Manaus, where the P1 variant is believed to have originated. Naveca said the changes appeared to be similar to the mutations seen in the even more aggressive South African variant, against which studies have shown some vaccines have substantially reduced efficacy.

“This is particularly worrying because the virus is continuing to accelerate in its evolution,” he added. Studies have shown the P1 variant to be as much as 2.5 times more contagious than the original coronavirus and more resistant to antibodies. On Tuesday, France suspended all flights to and from Brazil in a bid to prevent the variant’s spread as Latin America’s largest economy becomes increasingly isolated. The variant, which has quickly become dominant in Brazil, is thought to be a large factor behind a massive second wave that has brought the country’s death toll to over 350,000 - the second highest in the world behind the United States.  Brazil’s outbreak is also increasingly affecting younger people, with hospital data showing that in March more than half of all patients in intensive care were aged 40 or younger. For Ester Sabino, a scientist at the faculty of medicine of the University of Sao Paulo who led the first genome sequencing of the coronavirus in Brazil, the mutations of the P1 variant are not surprising given the fast pace of transmission. “If you have a high level of transmission, like you have in Brazil at the moment, your risk of new mutations and variants increases,” she said. Fiocruz researchers including Naveca also recently described a novel variant descended from a different lineage to P1, and detected in the northeast of the country, that carried 14 defining mutations including the E484K change first noted in the South African variant (bit.ly/2RBhLKD).

Preliminary data from a study conducted at the University of Oxford indicates that the COVID-19 vaccine developed by AstraZeneca PLC is effective against the P1, or Brazilian, variant, a source with knowledge of the study told Reuters on Friday.  The data indicates that the vaccine will not need to be modified in order to protect against the variant, which is believed to have originated in the Amazonian city of Manaus, said the source, who requested anonymity as the results have not yet been made public. The source did not provide the exact efficacy of the vaccine against the variant. They said the full results of the study should be released soon, possibly in March.  Early results indicated the AstraZeneca vaccine was significantly less effective against the South African variant, which is similar to P1. South Africa subsequently paused the use of the vaccine in the country. The information comes as a plasma study published ahead of peer review on Monday (bit.ly/3bX3LBa) suggested the CoronaVac COVID-19 vaccine developed by China's Sinovac Biotech may not work effectively against the Brazilian variant. Responding to a request for comment, Fiocruz, which sent the samples that formed the basis of the AstraZeneca vaccine study, told Reuters it did not have any information on the study, as it was being led by AstraZeneca and the University of Oxford.  Representatives for AstraZeneca and the University of Oxford did not immediately respond to requests for comment. Brazil is currently confronting a brutal and long-lasting second wave of the coronavirus, hitting a daily record of 1,910 deaths on Wednesday. The P1 variant (also known as 20J/501Y.V3) is among the factors that epidemiologists believe is contributing to a rise in cases and deaths, and there has been concern in the scientific community about the variant’s resistance to vaccines.