Friday, March 04, 2022
Scientists seek to solve mystery of why some people do not catch Covid
Despite quite a bit of exposure, I have had no Covid symptoms, so I may be one of those mentioned below. I do generally have a very good immune system. With a bit of a nudge it even wiped out some stomach cancer. I have had two AstraZenica shots but we know that vaccines are all but useless against Omicron
Phoebe Garrett has attended university lectures without catching Covid; she even hosted a party where everyone subsequently tested positive except her. “I think I’ve knowingly been exposed about four times,” the 22-year-old from High Wycombe said.
In March 2021, she participated in the world’s first Covid-19 challenge trial, which involved dripping live virus into her nose and pegging her nostrils shut for several hours, in a deliberate effort to infect her. Still her body resisted.
“We had multiple rounds of tests, and different methods of testing: throat swabs, nose swabs, other types of swabs that I’d never done before like nasal wicks – where you hold a swab in your nose for a minute – as well as blood tests, but I never developed symptoms, never tested positive,” Garrett said. “My mum has always said that our family never gets flu, and I’ve wondered if there’s maybe something behind that.”
Most people know someone who has stubbornly resisted catching Covid, despite everyone around them falling sick. Precisely how they do this remains a mystery, but scientists are beginning to find some clues.
The hope is that identifying these mechanisms could lead to the development of drugs that not only protect people from catching Covid, but also prevent them from passing it on.
Garrett is not the only challenge trial participant to have avoided becoming infected. Of the 34 who were exposed to the virus, 16 failed to develop an infection (defined as two consecutive positive PCR tests) – although around half of them transiently tested positive for low levels of the virus, often several days after exposure.
Possibly, this was a reflection of the immune system rapidly shutting down an embryonic infection. “In our previous studies with other viruses, we have seen early immune responses in the nose that are associated with resisting infection,” said Prof Christopher Chiu at Imperial College London, who led the study. “Together, these findings imply that there is a struggle between the virus and host, which in our ‘uninfected’ participants results in prevention of infection taking off.”
Some of them also reported some mild symptoms, such as a stuffy nose, sore throat, tiredness, or headache – although, since these commonly occur in everyday life, they may have been unrelated to virus exposure.
“Either way, levels of the virus didn’t climb high enough to trigger detectable levels of antibodies, T cells or inflammatory factors in the blood that are usually associated with symptoms,” Chiu said.
Other studies also suggest it is possible to shake off Covid during the earliest stages of infection, before it establishes a proper foothold. For instance, during the first wave of the pandemic, Dr Leo Swadling at University College London and colleagues intensively monitored a group of healthcare workers who were regularly exposed to infected patients, but who never tested positive or developed antibodies themselves. Blood tests revealed that around 15% of them had T cells reactive against Sars-CoV-2, plus other markers of viral infection.
Possibly, memory T-cells from previous coronavirus infections – ie those responsible for common colds – cross-reacted with the new coronavirus and protected them from Covid.
Understanding how frequently people abort nascent Covid infections in the era of Omicron is complicated because it requires intensive testing – for the virus, antibodies, T cells and other markers of infection – and because so many people have been vaccinated.
“It is likely vaccinated individuals are exposed to the virus, and block viral replication and detectable infection more commonly,” Swadling said.
There is also no commercially available test that can distinguish between immunity triggered by vaccination and the different variants – so unless a person has recently tested positive, it is almost impossible to know if they have been exposed to Omicron or not.
Seasonal coronaviruses may not be the only source of cross-protective immune responses. Prof Cecilia Söderberg-Nauclér, an immunologist at the Karolinska Institute in Stockholm, began investigating this possibility, after Sweden avoided being overwhelmed by cases during the pandemic’s first wave, despite its light-touch approach to restrictions. Mathematical modelling by her colleague, Marcus Carlsson at Lund University, suggested this pattern of infections could only be explained if a large proportion of people had some kind of protective immunity.
Her team scoured databases of protein sequences from existing viruses, hunting for small segments (peptides) resembling those from the new coronavirus, to which antibodies were likely to bind. When they identified a six-amino acid peptide in a protein from H1N1 influenza that matched a crucial part of the coronavirus spike protein, “I almost fell out of my chair,” Söderberg-Nauclér said.
They have since discovered antibodies to this peptide in up to 68% of blood donors from Stockholm. The research, which has not yet been peer-reviewed, could suggest that immune responses triggered by H1N1 influenza – which was responsible for the 2009-10 swine flu pandemic – and possibly related subsequent strains, may equip people with partial, though not complete, protection against Covid-19. “It provides a cushion, but it won’t protect you if an infected person coughs in your face,” Söderberg-Nauclér said.
A small proportion of people may even be genetically resistant to Covid-19. In October, an international consortium of researchers launched a global hunt to find some of them, in the hope of identifying protective genes.
“We are not looking for common gene variants that provide modest protection against infection, what we are looking for is potentially very rare gene variants that completely protect someone against infection,” said Prof András Spaan at the Rockefeller University in New York, who is leading the research.
They are particularly interested in people who shared a home and bed with an infected person, and avoided infection themselves. “For instance, the other day I was talking to an elderly lady from the Netherlands, who took care of her husband during the first wave. The husband was eventually admitted to the ICU, but she spent the week before taking care of him, sharing the same room, and without access to face masks,” said Spaan. “We cannot explain why she did not get infected.”
Such resistance is known to exist for other diseases, including HIV, malaria, and norovirus. In these cases, a genetic defect means some people lack a receptor used by the pathogen to enter cells, so they cannot be infected. “It could well be that, in some individuals, there is such a defect in a receptor used by Sars-CoV-2,” Spaan said.
Identifying such genes could lead to the development of new treatments for Covid-19, in the same way that the identification of CCR5 receptor defects in HIV-resistant people has led to new ways of treating HIV.
Spaan thinks it is unlikely that the majority of those who have avoided Covid are genetically resistant, even if they have some partial immune protection. This means there is no guarantee they will not eventually become infected – as Garrett found out in late January. Having dodged the virus for almost two years, she was shocked when a routine lateral flow test produced an ominous second red line. Shortly afterwards, she developed mild Covid symptoms, but has since recovered.
The irony is that, having avoided catching Covid from close family, friends and in a specialist medical laboratory, it was probably a relative stranger who infected her. “I have no idea where I got it from; it could have been someone in my local choir, or maybe from the gym,” she said.
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Time to Defund Vaccine and Mask Mandates
President Biden has declared victory over COVID. Congress should take him at his word and defund all of the vaccine and mask mandates now.
Just two weeks ago, Congress received 25 million emails urging them to defund the vaccine mandates in the Continuing Resolution to fund the government. Unfortunately, the Senate failed to do the job by voting 46-47 against a Senator Mike Lee vaccine mandate defund amendment and 44–49 against a separate amendment to defund mask requirements by Senator Ted Cruz.
The vaccine mandate defund amendment lost because four GOP Senators, Lindsey Graham, Mitt Romney, James Inhofe and Richard Burr chose to miss the vote.
Now, with every member of Congress able to be in the Capitol mask free as Democratic pollsters cry to their clients that they need to get beyond COVID for their political survival in November, defunding the enforcement of President Biden’s vaccine mandates in the upcoming Omnibus funding bill must be a Congressional priority.
Even the far left Fairfax County School District, where many federal bureaucrats send their children, have ended their mask requirements. The Washington, D.C. government, a vanguard of wokeness, has ended their draconian vaccine passport policy that prevented the unvaccinated from eating in restaurants or going into hotels, even as they were allowed to work in those same establishments.
But unless Congress defunds the enforcement of the regulations and Executive Orders mandating vaccinations, these onerous restrictions will linger in our health care systems, military, federal civil service and defense contractors like the sword of Damocles hanging over the heads of employees.
The enforcement of many of these edicts remains unresolved in the federal Courts but the threat to people’s livelihoods will remain so long as the regulations and Executive Orders remain on the books unless Congress defangs them through refusing to provide funding for their enforcement.
This should not be controversial. With Democrats desperate to move on from COVID, there should not be a single vote in the House or Senate against Congress asserting their rightful power of the purse by ending funding for the enforcement of these mandates. Not one.
As rare as it might be, this is one time when both those who supported and opposed the mandates should be able to agree that they should be ripped out by the roots rather than being left on the books like dangling live electrical wires waiting to shock unsuspecting passersby who inadvertently brush up against them.
At this time in history, we need every health care worker working. We need every member of our armed services ready to jump into action. We need our federal contractors planning to potentially ramp up production of military equipment and materiel. What we don’t need is for leaders in these areas to worry about the application of arbitrary and out-of-date health rules. We don’t need those who work in these fields looking over their shoulders out of concern for their livelihood due to their religious or health-related choice to not get vaccinated.
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Also see my other blogs. Main ones below:
http://edwatch.blogspot.com (EDUCATION WATCH)
http://antigreen.blogspot.com (GREENIE WATCH)
http://pcwatch.blogspot.com (POLITICAL CORRECTNESS WATCH)
http://australian-politics.blogspot.com/ (AUSTRALIAN POLITICS)
http://snorphty.blogspot.com/ (TONGUE-TIED)
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