Scientists mystified, wary, as Africa avoids Covid disaster

“We went into this project thinking we would see a higher rate of negative outcomes in people with a history of malaria infections because that’s what was seen in patients co-infected with malaria and Ebola,” said Jane Achan, a senior research advisor at the Malaria Consortium and a co-author of the study. “We were actually quite surprised to see the opposite — that malaria may have a protective effect.”

‘Achan said this may suggest that past infection with malaria could “blunt” the tendency of people’s immune systems to go into overdrive when they are infected with COVID-19. The research was presented Friday at a meeting of the American Society of Tropical Medicine and Hygiene.’

Read here (Associated Press, Nov 20, 2021)

Biolidics develops test detecting a person’s protective immunity against Covid-19; shares jump

‘Biolidics said the ClearEpi NAB Test is intended for the qualitative detection of circulating human IgG  antibodies capable of attaching to the Covid-19 spike proteins and preventing binding. "The company wishes to highlight that the ClearEpi NAB Test is intended for use as an aid in identifying individuals with an adaptive immune response to Sars-CoV-2 and should not be used to diagnose or exclude acute Sars-CoV-2 infection," Biolidics added.

‘Biolidics expects the development of the test and the receipt of the CE marking to contribute positively to its revenue for the financial year ending Dec 31, 2021, provided the company is able to successfully market and commercialise the test in the EU.’

Read here (Straits Times, Sept 15, 2021)

New studies find evidence of 'superhuman' immunity to Covid-19 in some individuals

‘So who is capable of mounting this "superhuman" or "hybrid" immune response? People who have had a "hybrid" exposure to the virus. Specifically, they were infected with the coronavirus in 2020 and then immunized with mRNA vaccines this year. "Those people have amazing responses to the vaccine," says virologist Theodora Hatziioannou at Rockefeller University, who also helped lead several of the studies. "I think they are in the best position to fight the virus. The antibodies in these people's blood can even neutralize SARS-CoV-1, the first coronavirus, which emerged 20 years ago. That virus is very, very different from SARS-CoV-2."

Read here (NPR, Sept 7, 2021)

What we actually know about waning immunity

‘Vaccines don’t last forever. This is by design: Like many of the microbes they mimic, the contents of the shots stick around only as long as it takes the body to eliminate them, a tenure on the order of days, perhaps a few weeks.

‘What does have staying power, though, is the immunological impression that vaccines leave behind. Defensive cells study decoy pathogens even as they purge them; the recollections that they form can last for years or decades after an injection. The learned response becomes a reflex, ingrained and automatic, a “robust immune memory” that far outlives the shot itself, Ali Ellebedy, an immunologist at Washington University in St. Louis, told me. That’s what happens with the COVID-19 vaccines, and Ellebedy and others told me they expect the memory to remain with us for a while yet, staving off severe disease and death from the virus at extraordinary 

‘That prediction might sound incompatible with recent reports of the “declining” effectiveness of COVID-19 vaccines, and the “waning” of immunity. According to the White House, we’ll all need boosters very, very soon to fortify our crumbling defenses. The past few weeks of news have made it seem as though we’re doomed to chase SARS-CoV-2 with shot after shot after shot, as if vaccine protections were slipping through our fingers like so much sand.’

Read here (The Atlantic, Sept 3, 2021)

How long does immunity last after Covid vaccination? Do we need booster shots? 2 immunology experts explain

‘As the rollout of COVID-19 vaccines continues, public attention is increasingly turning to booster shots, which aim to top up immunity if it wanes. But is a third dose needed? And if so, when? Let’s take a look at what the data tell us so far about how long immunity from COVID-19 vaccines might last.

• First, what about immunity following COVID-19 infection?
• How long does immunity from vaccines last?
• What about Delta?
• OK, so what now?

Read here (The Conversation, Aug 30, 2021)

New Covid variants have changed the game, and vaccines will not be enough. Lancet Covid-19 Commission calls for global ‘maximum suppression’

‘Put simply, the game has changed, and a successful global rollout of current vaccines by itself is no longer a guarantee of victory... No one is truly safe from COVID-19 until everyone is safe. We are in a race against time to get global transmission rates low enough to prevent the emergence and spread of new variants. The danger is that variants will arise that can overcome the immunity conferred by vaccinations or prior infection.

‘What’s more, many countries lack the capacity to track emerging variants via genomic surveillance. This means the situation may be even more serious than it appears.

‘As members of the Lancet COVID-19 Commission Taskforce on Public Health, we call for urgent action in response to the new variants. These new variants mean we cannot rely on the vaccines alone to provide protection but must maintain strong public health measures to reduce the risk from these variants. At the same time, we need to accelerate the vaccine program in all countries in an equitable way. Together, these strategies will deliver “maximum suppression” of the virus.’

Read here (The Conversation, Apr 6, 2021)

Download report here (Lancet Covid-19 Commission Taskforce on Public Health,  March 2021)

Rare Covid reactions might hold key to variant-proof vaccines

 ‘Some people mount an immune response able to fend off a menagerie of coronavirus variants...

‘Some of the vaccines that have been administered to millions of people might already be triggering variant-resilient immune responses. In another March preprint, a long-running COVID-19 study in Seattle, Washington, reported that after receiving a single dose of an mRNA vaccine, participants who had previously been infected with SARS-CoV-2 produced heaps of antibodies that can neutralize B.1.351, as well as an earlier circulating variant8. Those people also produced much higher levels of antibodies than typically seen even in those who have received two vaccine doses.

‘Leonidas Stamatatos, an immunologist at the Fred Hutchinson Cancer Research Center (FHCRC) in Seattle who co-led the study, suspects that a single vaccine dose boosted the levels of pre-existing antibodies that were capable of recognizing diverse variants. It’s not clear how to mimic this response in people who haven’t had COVID-19. One possibility is that a lag of several months between infection and vaccination was responsible, and that its effect could be replicated with another vaccine dose, given six months or a year after the first two, says Andy McGuire, an FHCRC immunologist who co-led the study.’

Read here (Nature, March 19, 2021)

The vaccine alternatives for people with compromised immune systems

‘While the exact number of the immunocompromised worldwide is unknown, estimates suggest that about 10 million live in the U.S. alone, or around 3 percent of the national population. The number encompasses a diverse range of vulnerabilities, including rare genetic immune deficiencies, chronic illnesses that impair the immune system such as rheumatoid arthritis, and cancer and organ-transplant patients who must take immune-suppressing medications.

‘For them, vaccines will not be effective, because they are incapable of making their own antibodies to neutralize the SARS-CoV-2 virus. Instead, pharmaceutical companies around the world are racing to develop alternative treatments that bypass the immune system altogether.

‘The most common option is called monoclonal antibody treatments. These artificially generated antibodies mimic the body’s natural immune response by binding to key sites on the virus’ spike protein, preventing it entering cells and reproducing. Companies including AstraZeneca, Regeneron, and Eli Lilly are currently testing whether monoclonal antibodies can protect immunocompromised people from SARS-CoV-2.’

Read here (National Geographic, Feb 4, 2021)

Can you still transmit Covid-19 after vaccination?

‘In fact, most vaccines don't fully protect against infection, even if they can block symptoms from appearing. As a result, vaccinated people can unknowingly carry and spread pathogens. Occasionally, they can even start epidemics. 

"Effective" or "sterilising" immunity: There are two main types of immunity you can achieve with vaccines. One is so-called "effective" immunity, which can prevent a pathogen from causing serious disease, but can't stop it from entering the body or making more copies of itself. The other is "sterilising immunity", which can thwart infections entirely, and even prevent asymptomatic cases. The latter is the aspiration of all vaccine research, but surprisingly rarely achieved.

What type of immunity do the Covid-19 vaccines provide? "In a nutshell we don't know, because they’re too new," says Neal. So far, the available Covid-19 vaccines have not been judged primarily on their ability to prevent transmission – though this is now being evaluated as a secondary endpoint for many of them. Instead, their efficacy was assessed by whether they could prevent symptoms from developing. "This means that we set our targets kind of pragmatically," says Danny Altmann, professor of immunology at Imperial College London.’

Read here (BBC, Feb 4, 2021)

Could mixing Covid vaccines boost immune response?

‘Vaccine developers often combine two vaccines to combat the same pathogen, and researchers are keen to deploy the strategy — known as a heterologous prime-boost — against the coronavirus. A heterologous prime-boost combination was approved last year by European regulators to protect against Ebola, and experimental HIV vaccines often rely on the strategy, says Dan Barouch, director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center in Boston, Massachusetts. But it has yet to be tested for vaccines against COVID-19, which are typically given as a repeat injection of the same vaccine.

‘The ability to mix and match vaccines could make vaccination programmes more flexible: it would speed up the process and reduce the impact of any supply-chain disruptions. “It really makes the implementation much more simple,” said Mary Ramsay, head of immunization at Public Health England, at a press briefing on 3 February.’

Read here (Nature, Feb 4, 2021)

Past Covid-19 infection may provide 'months of immunity'

‘Most people who have had Covid-19 are protected from catching it again for at least five months, a study led by Public Health England shows. Past infection was linked to around a 83% lower risk of getting the virus, compared with those who had never had Covid-19, scientists found.

‘But experts warn some people do catch Covid-19 again - and can infect others. And officials stress people should follow the stay-at-home rules - whether or not they have had the virus.’

Read here (BBC, Jan 14, 2021) 

Travel body rejects compulsory COVID-19 shots as experts say herd immunity not close

‘Some policymakers have proposed immunisation should be compulsory for air travel as the world steps up the battle to curb the spread of Covid-19, and Australia's Qantas Airways has said it plans to introduce such a requirement. But Ms Gloria Guevara, chief executive of the World Travel and Tourism Council, said such moves would be similar to workplace discrimination.

"We should never require the vaccination to get a job or to travel," Ms Guevara, whose organisation represents a sector that has been badly hit by the pandemic and accounts for as much as 10 per cent of global employment, told a panel at Reuters Next.’

Read here (Reuters, Jan 11, 2021)

The mysterious link between Covid-19 and sleep

‘The coronavirus can cause insomnia and long-term changes in our nervous systems. But sleep could also be a key to ending the pandemic... 

‘The newly discovered coronavirus had killed only a few dozen people when Feixiong Cheng started looking for a treatment. He knew time was of the essence: Cheng, a data analyst at the Cleveland Clinic, had seen similar coronaviruses tear through China and Saudi Arabia before, sickening thousands and shaking the global economy. So, in January, his lab used artificial intelligence to search for hidden clues in the structure of the virus to predict how it invaded human cells, and what might stop it. One observation stood out: The virus could potentially be blocked by melatonin...

‘After he published his research, though, Cheng heard from scientists around the world who thought there might be something to it. They noted that, in addition to melatonin’s well-known effects on sleep, it plays a part in calibrating the immune system. Essentially, it acts as a moderator to help keep our self-protective responses from going haywire—which happens to be the basic problem that can quickly turn a mild case of COVID-19 into a life-threatening scenario.’

Read here (The Atlantic, Dec 22, 2020)

How kids’ immune systems can evade Covid

‘Their immune system sees the virus “and it just mounts this really quick and effective immune response that shuts it down, before it has a chance to replicate to the point that it comes up positive on the swab diagnostic test”, says Melanie Neeland, an immunologist who studied the family, at the Murdoch Children’s Research Institute in Melbourne, Australia.

‘Even in children who experienced the severe but rare complication called multisystem inflammatory syndrome in response to SARS-CoV-2 infection, studies report that the rate of positive results on RT-PCR range from just 29% to 50%.‘

Read here (Nature, Dec 10, 2020)

Babies born to mums with Covid-19 may have antibodies, but scope of protection is unclear

‘Although babies of women infected with Covid-19 during their pregnancies have been born with antibodies, it remains unclear if this means the baby is immune to the coronavirus or how long the immunity would last. Earlier this month, Mrs Celine Ng-Chan, 31, gave birth to her second child and was told by her son's paediatrician that he has antibodies against the virus.’

Read here (Straits Times, Nov 29, 2020)

Three Australian kids baffle doctors after developing Covid antibodies without ever testing positive: Study published in Nature Communications

‘The kids – aged six, seven and nine – took the COVID-19 test and the results were negative. “It was jaw-droppingly amazing because they'd spent a week and a half with us while we were COVID-positive,” added the mother. While two kids had mild symptoms, one daughter remained completely asymptomatic. They were tested again, just to get negative results. This continued for several weeks, until everyone in the family tested negative.

‘What surprised the doctors was when the results came negative despite the polymerase chain reaction (PCR) tests of the kids showing antibodies of Sars-CoV-2. This definitely caused curiosity as the kids never tested positive for the virus. While the researchers are keen to do a further study on the immune response of the kids, paediatrician Shidan Tosif from the University of Melbourne said, “The fact these children were able to shut down the virus and without even showing a positive test result suggests they have some level of their immune system which is able to respond and deal effectively with the virus, without them ever becoming very unwell.”

Read here (Yahoo News, Nov 19, 2020)  

‘Mutant coronavirus’ seen before on mink farms, say scientists

‘The coronavirus mutation causing concern in Denmark has arisen before in mink, scientists have revealed. The mutated virus has been detected retrospectively in mink at a farm in the Netherlands, but it did not spread to humans, said a leading Dutch expert...

‘The genetic data from Denmark was released on an international database a few days ago, with some scientists questioning why it had not been released sooner. "I think that it is most disappointing that the data have only just reached the light of day," said Prof James Wood, head of the department of veterinary medicine at the University of Cambridge, UK...

‘Six countries have reported coronavirus outbreaks at mink farms: the Netherlands, Denmark, Spain, Sweden, Italy and the US.’

Read here (BBC, Nov 9, 2020)

Coronavirus: Fact checks on immunity and related matters

‘A large study out of the UK suggests immunity after a COVID-19 infection reduces fast, especially among older people. This is a quick fact check on the following: (1) How long am I immune after a COVID-19 infection? (2) Why does research on immunity differ? (3) Do people who have recovered from a COVID-19 infection continue to use protective measures? (4) Do some people, who have had a COVID-19 infection, show no immunity?’

Read here (DW, Oct 28, 2020)

A flu shot might reduce coronavirus infections, early research suggests

‘In the new study, Mihai Netea, an infectious disease immunologist at Radboud University Medical Center in the Netherlands, and his colleagues combed through their hospital’s databases to see if employees who got a flu shot during the 2019–2020 season were more or less likely to get infected by SARS-CoV-2, the virus behind COVID-19. Workers who received a flu vaccine, the researchers found, were 39 percent less likely to test positive for the coronavirus as of June 1, 2020. While 2.23 percent of nonvaccinated employees tested positive, only 1.33 percent of vaccinated ones did. Netea and his team posted their findings on the preprint server MedRxiv on October 16.’

Read here (Scientific American, Oct 27, 2020)

How anti-ageing drugs could boost Covid vaccines in older people

‘Unlike fine wine, the human body does not improve with age. Hearing fades, skin sags, joints give out. Even the body’s immune system loses some of its vigour. This phenomenon, known as immunosenescence, might explain why older age groups are so hard-hit by COVID-19. And there is another troubling implication: vaccines, which incite the immune system to fight off invaders, often perform poorly in older people. The best strategy for quelling the pandemic might fail in exactly the group that needs it most...

‘[Eric] Verdin [president and chief executive of the Buck Institute for Research on Aging in Novato, California] agrees that supporting the older immune system should be a priority. “I think the net result of all this will be renewed interest in understanding the defect in the immune response in the elderly.” That has implications not only for the coronavirus, but also for a host of other diseases, including other viral infections and even cancer. “COVID-19 has brought to the front something that a lot of people have ignored.”

Read here (Nature, Oct 14, 2020)