The coronavirus strain that took South Africa by storm with its incredible ability to infect people who were already ill with COVID-19 is now in California and at least three other states. More than any other version of the virus, it has proven that it can evade the vaccines designed to block it.
Is another upsurge fueled by South African tensions inevitable here?
Rare. The coronavirus that develops has a lot of tricks up its sleeve, but scientists say so too.
Evidence that various vaccines are less effective in neutralizing tensions from South Africa is ‘disturbing news’, but ‘all is not lost’, said Dr. Anthony Fauci, the country’s leading expert on infectious diseases, said. Vaccination “continues to suppress the virus,” he said.
And while the emergence of new variants that can ‘escape’ some of the antibodies from the immune system is worrying, the endless hand-wringing is ‘a story we need to fix’, said Larry Luchsinger, a scientist from the New York Blood, said. Centre.
After nearly a year of woe and worry, the latest challenge of the pandemic has brought an unusually bright side to many scientists. Yes, there is water waste, they say. But they quickly point out that this glass is still more than half full.
Why? Because numbers matter, and even an elusive target such as the South African variant is unlikely to completely escape the overwhelming number of antibodies generated by current vaccines or a previous infection, Luchsinger said.
The concern was raised by clinical trials involving several COVID-19 vaccines.
For example, a Johnson & Johnson vaccine that reduced the risk of moderate to severe cases of COVID-19 in the US by 72% was only 57% effective in reducing the risk in South Africa, where the coronavirus strain is known. if B.1.351 dominates. Similarly, a Novavax vaccine that reduced the risk of all types of COVID-19 by almost 90% in the UK was only 49% effective in South Africa.
The difference can also be seen by comparing clinical trials at different time points. When the COVID-19 vaccine developed by AstraZeneca and the University of Oxford was tested in South Africa a few months ago, those who received it were 75% less likely to develop mild to moderate illnesses than theirs. peers who received a placebo. But after taking over B.1.351, the AstraZeneca vaccine offers no advantage over the placebo.
Tests performed in laboratory settings were also important. For example, antibodies generated by people who received the Pfizer-BioNTech vaccine were not as effective at blocking a engineered version of the virus from South Africa as at the manufactured versions of another strain from the United States. Kingdom to stop, according to the results published this week in the journal Nature Medicine.
Understanding why these seemingly disturbing developments do not panic scientists helps to know that the process by which antibodies neutralize free-floating viral particles is a chaotic, inefficient, and repetitive game of hit-and-miss.
Whether caused by vaccination or natural infection, antibodies are regularly attached to their viral invaders, dropped off and new ones set in to take their place. The inefficiency requires the immune system to build up legions of neutralizing antibodies that are diverse and abundant enough to overwhelm more viral targets than most infections can provide, Luchsinger said.
Even when a virus gets a mutation that makes antibodies less capable of neutralizing its targets, there is still so much redundancy that the virus remains vulnerable, he said.
Scientists from Caltech and Rockefeller University saw this when they placed antibodies induced by the Pfizer-BioNTech vaccine and a similar one from Moderna against several of the new coronavirus variants.
The researchers extracted antibodies from 20 vaccinated volunteers. In laboratory dishes, those antibodies could “strongly neutralize” any coronavirus variant that researchers throw at them, according to a study published in the journal Nature this week.
The sunny picture was clouded – but not obscured – by a worrying finding: if you just look at the 17 most powerful antibodies produced in response to the two vaccines, the neutralizing effect was ‘reduced or abolished’ in 14 cases by the mutation called E484K, one of the characteristics of the South African tribe.
This may sound worrying, but it’s actually the power of the immune system’s response to these specific vaccines. If the antibodies and other immune proteins generated by vaccination were a team, the bank would be so deep that 14 of its 17 top players could be injured or sent to the locker room, and it would still dominate South Africa’s viral variant.
Even if viruses evade some antibodies, the adaptive immune system lives up to its name. After meeting with the South African tribe to learn to recognize the original Wuhan virus, either through a vaccine or a previous infection, the body’s white blood cells are asked to emit antibodies that get better. to target the altered virus.
“It fits,” Luchsinger said.
Indeed, this probably explains why vaccines that have a reduced efficacy against the South African variant still work well enough to prevent serious diseases, hospitalization and the death of COVID-19.
In South Africa, researchers remain hopeful that the AstraZeneca vaccine will follow this pattern. In the most recent experiment there, none of the participants contracted serious diseases, so the jury is not yet available.
“This vaccine can still at least protect against severe COVID-19, especially in individuals at high risk of developing serious diseases,” said Dr. Shabir Madhi, a vaccination expert at the University of the Witwatersrand in Johannesburg, said. This is perhaps the most one can expect from a vaccine, he added.
Scientists are also encouraged that the South African tribe no longer looks transferable than its predecessors. Although it has reached U.S. shores, it is unlikely to spread aggressively. This will give us more time to step up the vaccinations and deny B.1.351 the chance to gain a firm foothold here, Fauci said.
Dr. Stanley Perlman, a microbiologist at the University of Iowa who has been studying coronaviruses for decades, said he was overwhelmed by genetic changes that made South Africa better able to evade antibodies, but apparently no longer transmissible. Overall, he said, a virus’ best strategy is to keep an outbreak and to find new hosts, to change in a way that can spread it more easily.
Perlman suspects one of B.1.351’s mutations is doing something sneaky – such as improving the virus’ ability to enter cells – which has not yet been executed. There may still be surprises ahead, he said.
But there is also a backup plan for it. As researchers sort out the mutations they see emerging, they learn more about what each change does, what troublemakers are, and how they can work together.
Insights like these will help them reformulate vaccines to improve their effectiveness and to create enhancers for people who have already been vaccinated.
“This is not a leading person if the virus continues to develop, which I expect,” said Dr. Bruce Walker, the founding director of the Ragon Institute in Boston, devoted himself to the study of the immune system. “We treat flu every year” by reformulating the vaccine. “We can do it here.”
Scientists are also uncovering the virus’ secrets. Repetitive patterns of mutations emanating from different corners of the world have given them clues as to which strategies increase the fitness of the virus. This in turn indicates which virus structures are most likely to change, and how.
“The virus tells us what it’s comfortable with,” Walker said, adding that knowledge could help scientists anticipate the next step.