Friday, April 02, 2021

Pfizer Covid vaccine 'is 100% effective against South African variant, beats Brazilian strain' AND works for at least six months

Pfizer's coronavirus vaccine is still 91 percent effective at preventing COVID-19, offers six months of protection and does work against worrisome South African variant, new firm data reveal.

In fact, the shot was 100 percent effective in preventing illness among trial participants in South Africa, where a new variant called B1351 is dominant, although the number of those participants was relatively small at 800.

Dr Anthony Fauci called the results 'really very encouraging,' in a Thursday CBS interview.

While the new overall efficacy rate of 91.3 percent is lower than the 95 percent originally reported in November for its 44,000-person trial, a number of variants have become more prevalent around the world since then.

However, the shot was more effective in the U.S., preventing nearly 93 percent of symptomatic infections.

Pfizer previously only had data to suggest the shot's protection lasted nine months. The new data is the largest real-world test of the shot since its approval and doubles the duration of vaccine immunity.

It comes at a critical moment, when variants are taking hold in the U.S., and as the nation will look to Pfizer and Moderna to make up for ten of millions of doses of Johnson & Johnson's one-shot vaccine lost to human error.

To-date, the U.S. has given one or more vaccine doses to nearly 30 percent of Americans and more than 16 percent of people are fully vaccinated

Pfizer's Chief Executive Officer Albert Bourla said the updated results, which includes data on more than 12,000 people fully inoculated for at least six months, positions the drugmakers to submit for full U.S. regulatory approval.

The vaccine is currently authorized on an emergency basis by the U.S. Food and Drug Administration (FDA).

The trial data 'provide the first clinical results that a vaccine can effectively protect against currently circulating variants, a critical factor to reach herd immunity and end this pandemic for the global population,' Ugur Sahin, chief executive officer at BioNTech, said in a statement.

Experts fear new variants of COVID-19 from South Africa and Brazil may be resistant to existing vaccines and treatment.

More than 300 cases of the South African variant have been detected in more than 25 U.S. states and jurisdictions, according to federal data.

Pfizer and University of Birmingham researchers found that the the vaccine triggers protective antibodies against the Brazil variant.

In Pfizer's real-world study, the vaccine was 100 percent effective in preventing severe disease and death in the small South African trial, and 95.3 percent effective in preventing severe disease in the overall trials.

It was 91.3 percent effective at preventing symptomatic infection, overall.

Researchers identified 927 total cases of COVID-19 among the more than 46,000 members of the original trial.

Of those, 850 cases were in people who received a placebo shot. Just 77 infections were found among the participants who got the real vaccine.

The shot's efficacy was even higher in the U.S., where just 50 of the 697 total COVID-19 cases occurred in people who got the vaccine. The remaining cases were among participants who got the placebo shot.

Based on those results, the shot was 92.6 percent effective in the U.S.

All nine COVID-19 cases that arose among the 800 South African participants were in the placebo group.

South Africa's variant appeared in lab tests to dull the effects of antibodies triggered by vaccines in the lab, prompting alarm worldwide that the variant would render a year of frantic shot development useless.

The variant, known as B1351, is now dominant in South Africa and has spread to many other countries - including the U.S. and UK, but is not dominant in most other regions -

In fact, AstraZeneca shot performed so poorly against the South African variant that the nation gave its allocation away.

Pfizer's latest findings bring a sigh of relief that the vaccine will still work against the more infectious variant that emerged there.

And Americans who got vaccinated with Pfizer's shot in December can rest assured that they still have immunity.

Pfizer had only followed a sizable share of its trial participants for three months when its vaccine was authorized by the FDA in December.

Now, at least 12,000 of those participants have been vaccinated for six months and the shot's efficacy remains over 90 percent.

Protection likely extends well beyond that duration, too, but has yet to be proven.

That's an encouraging sign that the incoming supply of Pfizer's vaccine won't need to be used as booster shots and can be used to get more people vaccinated.

The U.S. will need that supply, especially after 15 million doses of Johnson & Johnson's vaccine were ruined by an ingredient mix-up and forced a halt on next month's supply of the one-dose shot, the New York Times reported Wednesday.

Fortunately, Pfizer is ahead of its production schedule, and Moderna will soon be able to ship 40 percent more vaccine in each of its vials, a drastic increase to the overall supply.

There were also no serious safety concerns observed in Pfizer trial participants up to six months after the second dose, the companies said.

Johnson & Johnson will meet its goal of delivering 20 million doses of its one-dose COVID-19 vaccine to the U.S. by the end of March, with a whopping 11 million doses shipping next week

They added that it was generally equally effective irrespective of age, race, gender or ethnicity, and among participants with a variety of existing medical conditions.

And earlier this month, data on health care and essential workers showed their risks of contracting symptomatic COVID-19 were reduced by 80 percent after the first dose of either Pfizer or Moderna's vaccine.

The release of Pfizer's updated results comes on the heels of separate data that showed the vaccine is safe and effective in 12- to 15-year olds, paving the way for the drugmakers to seek U.S. and European approval to use the shot in this age group within weeks.


COVID-19 is especially harsh on elderly people, and researchers think they know why

Australian researchers have been investigating why elderly people respond so poorly to COVID-19, and theorise that it's linked to their repeated exposure to other seasonal coronaviruses.

There are seven types of coronaviruses that can infect people (including SARS-CoV-2, the virus which causes COVID-19 disease), four of which are common causes of acute respiratory infections.

In a study published in Nature Communications, scientists looked at blood samples from 89 healthy children, 98 adults, 57 elderly individuals and 50 COVID-19 patients, comparing antibodies to a range of coronaviruses, including SARS-CoV-2.

Lead author Amy Chung, laboratory head at the Peter Doherty Institute for Infection and Immunity, said researchers hypothesised that when an elderly person was first exposed to SARS-CoV-2, their immune system viewed it as a typical, seasonal coronavirus instead of a new strain.

Dr Chung said in this case the immune memory wasn't helpful because the two were very different and needed different responses to fight off infection.

She likened the immune memory response to SARS-CoV-2 to playing sport, with an older person's immune system thinking it had taken on the virus before.

"You have an opponent, and for the elderly, this is someone that in their minds is a team they have played multiple times beforehand," she said. "They know the stats, and they know the key players to target."

By comparison, children (who overall had less exposure to human coronaviruses) saw SARS-CoV-2 as a new opponent.

"They're coming in without all these preconceptions of, 'hey, these are the stats, this is how it should be played' and therefore are inducing this fresh immunity, without this preconception, and are able to target really specific responses for COVID-19," Dr Chung said.

'Fundamentally different' immune cells

Vanessa Bryant from the Walter and Eliza Hall Institute said the study identified unique antibody responses in the elderly and children, and then compared these signatures to COVID-19 recovered adults.

It found a greater level of highly specialised antibodies in elderly people and more broad-functioning antibodies in children.

Dr Bryant said this difference in antibodies was not just a direct result of exposure to coronavirus.

"[But] more of an indirect relationship between an existing pool of antibodies against other coronaviruses in elderly people that can recognise SARS-CoV-2, and elderly people being more likely to have poor immune responses and develop severe COVID-19," she explained.

The theory proposed in the paper was that the pool of immune cells in elderly people and children was fundamentally different.

"Elderly people are drawing on a smaller pool of virus-naïve, or inexperienced, immune cells; instead they have a high number of coronavirus-experienced cells that may be selected because they can also recognise SARS-CoV-2," Dr Bryant said.

Selection of these already existing memory cells may skew their antibody response to antibodies that bind SARS-CoV-2 well, but are less effective at eliminating the virus, she explained.

"On the other hand, children, who have a more immature immune system, will have lots of virus-naïve cells to choose from, and perhaps this makes them more likely to find more 'perfect matches' for SARS-CoV-2 that bind strongly and can attack the virus effectively in multiple ways," Dr Bryant said.

University of Queensland professor of medicine Paul Griffin described the study as "incredibly interesting", but noted the small sample size used by researchers.

"Given the numbers in the study, all of the outcomes being reported are fairly preliminary and need to be validated by larger studies," he said.

Professor Griffin said this was especially the case in the number of COVID-19 patients examined, with only 50 people in the study itself.

People over the age of 70 are at a higher risk of serious illness from COVID-19, whereas research shows children don't tend to get as sick as older adults. This is unusual, because children often play a key role in the transmission and development of respiratory-type illnesses.

Dr Chung said researchers went into the project aiming to understand why elderly people were more susceptible to COVID-19, especially in comparison to children.

Prior to launching the study, Dr Chung said the team theorised that because kids regularly had respiratory-type illnesses caused by seasonal coronaviruses, this induced immune responses in children protected them from COVID-19.

"Our study actually showed the complete opposite," she said. "It showed that the elderly, due to their long lives, were repeatedly being exposed to seasonal coronaviruses."

Dr Bryant said experts had some data, and lots of ideas, about why children had a better response to COVID-19 to older adults.

One reason, she explained, could be the type of immune response in children versus adults.

"Another is that children have fewer ACE2 receptors on the cells lining their respiratory tract and lung," she said.

"SARS-CoV-2 hijacks this receptor as an entry point to infect cells. … fewer ACE2 receptors means less opportunity for the virus to infect cells and make millions of viral copies, a lower viral load also gives the immune system a fighting advantage."

Professor Griffin said while some of the paper's findings could explain why elderly patients were so susceptible to COVID-19 disease, it was likely to form part of the puzzle — not the whole picture.

"I think it's more complex, I don't think it will be explained solely by the differences outlined in this paper," he said.

Dr Bryant also said elderly people could also be immunocompromised, which led to a weaker immune response.

"There are lots of reasons for this. An elderly person may have more underlying conditions or undiagnosed health issues that dampen their ability to make a strong response," she said.

Dr Chung said there was "something really unique" about children's different response to SARS-CoV-2. "Kids had this ability to activate surrounding white blood cells … to come and clear the virus away," Dr Chung explained.

This was a significant finding, she said, because it was an understudied research area.

Dr Bryant said research had previously uncovered how important other immune cells could be fighting COVID-19 disease.

"A recent Australian study looked at immune responses in children and adults with mild disease from the same household," she explained.

"In particular, children made a robust response in one particular type of innate cell, neutrophils, and in some children, this response was so effective that the viral load was below detectable levels."




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