The Delta variant is, for many, the biggest threat posed by COVID-19 today. However, so far, data show that vaccines are working quite well against this variant, as the effectiveness of immunizers does not drop many percentage points. Nonetheless, health authorities, such as the Centers for Disease Control and Prevention (CDC), say they are constantly evaluating whether potential variants may be much stronger than the current variants and overcome vaccine immunity.
The CDC explains on its website that “New variants of the virus that causes COVID-19 are spreading in the United States and in other parts of the world. Current data suggest that COVID-19 vaccines authorized for use in the United States offer protection against most variants currently spreading in the United States. However, some variants might cause illness in some people even after they are fully vaccinated.”
They add, “evidence is limited on how the new COVID-19 variants will affect how COVID-19 vaccines work in real-world conditions. CDC will continue to monitor how vaccines are working to see if variants have any impact on how well COVID-19 vaccines work in real-world conditions.”
Directly, Dr. Anthony Fauci, chief medical advisor to the White House, said that “We are dealing with a different virus now” referring to the Delta variant and that is why the CDC changed its guidelines on the use of masks in indoor places for all people, including those vaccinated.
According to the Israeli Ministry of Health, the effectiveness of the vaccines in preventing a COVID-19 infection due to the outbreak of the Delta variant declined to 64 %, as did the ability to prevent an illness with symptoms. However, the efficacy of vaccines in preventing severe disease remains high at 93 %.
For example, Tom Frieden, former New York City Health Commissioner and also former CDC CEO, tweeted about it: “The emergence of future variants that can escape vaccine-induced immunity. Delta may not be the worst variant the virus deals us. Continued uncontrolled spread around the world makes this scenario more likely.”
This tweet prompted a reaction from renowned virologist Angela Rasmussen, who explained that new variants of Wuhan coronavirus are unlikely to “escape vaccine-induced immunity.”
Angela Rasmussen: “Our main concern should be to vaccinate the world”
In a lengthy thread on her Twitter account, Rasmussen laid out what the odds are that COVID-19 will mutate, generating new variants that break down vaccine immunity. For her, this is unlikely to happen due to several reasons, among them, that “The immune system is more complex than just neutralizing antibodies” and this can also be very effective in its development. Furthermore, to state that new variants may arrive would be making an assumption rather than a fact.
“We should worry about the future “worse” variants that will likely result from uncontrolled spread,” Rasmussen said before starting the thread. “But they are not likely to “escape vaccine-induced immunity.” There are several reasons why this is the case.”
“The immune system is more complex than just neutralizing antibodies. A few mutations in the N-terminal domain (NTD) or receptor-binding domain (RBD) of spike are insufficient to escape the totality of the immune response,” he explains. “The immune system is not a static wall. It’s more like a dynamic army, with specialized units that mobilize to attack an infection on multiple fronts. Acquiring a few point mutations in a single antigen are insufficient to evade these complex defenses.”
According to the virologist, the scientific community has long had data explaining that, “we’ve had data for some time that, while neutralizing antibodies can be impacted by mutations in key parts of spike (especially the RBD), T cells appear to be broadly cross-reactive for a variety of coronaviruses, including SARS-CoV-2.”
“T cells are a kind of immune cell, whose main purpose is to identify and kill invading pathogens or infected cells,” the BBC explains. “It does this using proteins on its surface, which can bind to proteins on the surface of these imposters.”
“We still don’t know the extent to which these cross-reactive T cells provide protection against COVID, but it’s very clear that vaccines induce both potent antibody and T cell responses. Keep in mind: antibodies and T cells are both diverse and exquisitely specific for SARS-CoV-2,” remarked Dr. Rasmussen in her thread, who went on to explain why it is complex for variants to break down vaccine immunity.
The COVID-19 variants are strong, but so is the immune system
The virologist insists that despite alarmist coverage of the variants, the reality is that the vaccines are still effective today.
“Despite alarmist coverage about “breakthrough infections,” the vaccines were actually evaluated w/ symptomatic COVID-19 as the primary endpoint, not infection,” she said. “Vaccine effectiveness is based on their ability to prevent disease, not prevent infection altogether (though they do the latter pretty well too). And the totality of responses produced by complete vaccination holds up well against the VOCs [variants].”
That said, she insisted that full vaccination is critically important, “Full vaccination creates a barrier to replication that is largely insurmountable for the virus. Partial vaccination, on the other hand, may not be. That’s why the one-shot mRNA regimes are a bad idea (and delayed dose strategies in the UK and here in Canada have borne that out).”
In short, for the doctor, there is a very remote possibility that a variant of COVID-19 can completely break down immunity and that, despite this, there are still defense mechanisms in our immune system that can fight the virus.
“So far there are 4 VOCs: alpha (B.1.1.7), beta (B.1.351), gamma (P.1), and delta (B.1.617.2). Alpha and delta are more transmissible. Beta and gamma can evade some neutralizing antibody responses. Who wins in a head to head competition? Alpha and delta, hands down,” Rasmussen explained. “Increased transmissibility in the unvaccinated is clearly an advantage, as alpha and delta have outcompeted beta and gamma over and over again. That’s because it’s not enough to evade some neutralizing antibody responses. All VOCs hit a dead end in most vaccinated people.”
” It is not transmission of beta and gamma among vaccinated people, but accelerated transmission in the unvaccinated that has allowed alpha and now delta to rapidly become dominant and is driving increasing case numbers,” she added.
The bottom line for the doctor is that we certainly “should remain vigilant.”
“We can’t rule out the possibility that VOCs will emerge that evade vaccines (those would probably be classified one step up, as variants of high consequence). Anything’s possible. But likely? In my opinion, no.”
“Viruses are unpredictable. While accelerated viral evolution is formidable, our immune systems are pretty fucking awesome too. For now, our biggest concern should be vaccinating the world, not worrying about hypothetical immune evasion that likely won’t happen.”