The coronavirus that causes COVID-19 (SARS-CoV-2) is probably never going to be eradicated. Even with a vaccine. The strongest evidence for this assertion came earlier this month in a preliminary research paper that hasn’t been scientifically reviewed yet that was posted on bioRxiv.
I know this will come as a disappointment, but before I get ahead of myself let me explain. Only two diseases have ever been completely eradicated. Both were caused by viruses. Rinderpest was an infectious viral disease that affected cattle, buffalo, and other species of even-toed ungulates that was caused by the rinderpest virus (RPV). Up until it was eradicated in 2011, rinderpest was considered one of the most fearsome and devastating diseases of domesticated animals.
The only human disease that has ever been eradicated is smallpox caused by the variola virus. Before it was officially declared eradicated in 1980, this scourge caused an estimated 300-500 million deaths in the twentieth century alone (representing around 10% of all people who died last century).
Until we were successful in wiping it out of existence, smallpox had played a huge role in human history and culture- from the genocidal decimation of the indigenous populations of the Americas (who had no immunity) by European colonizers to the curative powers of the goddess Ma Sitala prevalent in the part of India from where I hail. Swept up in the story of smallpox is brilliant Edward Jenner, the English doctor who first popularized the use of vaccines. All of this has been covered quite adeptly by Gareth Williams in Angel of Death: The Story of Smallpox, a book I highly encourage everyone to read.
Smallpox was prevalent in India until very recently. My father contracted smallpox and nearly died from it. In 1967 there were around 10 million cases of smallpox and 2 million deaths according to WHO estimates. A decade later there were zero. I’ve never had to worry about it in my lifetime.
The eradication of smallpox, as well as the reduction of deaths from other infectious diseases such as malaria and cholera are, in my mind, the greatest unheralded achievements in independent India. These achievements do not get the same exposure as Big Science- a nuclear explosion in the middle of the desert or the firing of a rocket into outer space, but they’ve arguably done more for improving life-span and the quality of life than any other achievement (though a possible argument can also be made for the agricultural Green Revolution).
What made smallpox a disease that could be eradicated gives us hope for certain other diseases like polio which are undergoing intensive eradication measures. It also explains why COVID-19 is likely here to stay for good. Because smallpox only infected humans, it was a good target for eradication.
With any infectious disease, there is a constantly emerging population of susceptible people are can be readily infected: these are newborns who do not have antibodies from immunization or exposure to the disease. Elderly people also have waning immune responses, known as senescence. But the crucial aspect of control of infectious diseases is early immunization, which provides both protection to the person and additively to the community. The infectious agent can’t access susceptible individuals and burns out.
The situation is much more complicated in the case of a virus like SARS-CoV-2 which can infect other animals that can now act as reservoir species. Even if we are able to undertake a massive eradication campaign with a very effective vaccine in humans, the virus will remain in the reservoir animal, poised to infect people who are susceptible. Let me elaborate this point.
Nearly all credible experts believe that SARS-CoV-2 originated in bats, from which they either directly infected humans (possibly years ago) or a second reservoir species en route to humans. In both cases, additional mutations would’ve made SARS-CoV-2 very infectious in people. (To the best of my knowledge, no credible scientist believes the virus was created in a lab).
People are now infecting other people. Human to human transmission is how SARS-CoV-2 spreads. Does this virus in its present mutated human-transmissible form exist in bats? It is unknown. Can infected people reinfect bats? Also unknown.
What we knew up until September is that under certain conditions, people can infect certain (but not all) animals. The American Veterinary Medical Association had this to say on its website, updated on June 11, 2020—
There have been fewer than 25 reports from around the world of pets (dogs and cats) being infected with SARS-CoV-2; however, none of these reports suggest that pets are a source of infection for people. Evidence to date from the few domestic animals that have tested positive for SARS-CoV-2 indicate these infections are typically a result of close contact with people with COVID-19. In laboratory studies of experimental infection with SARS-CoV-2, ferrets, Syrian hamsters, and cats—all animals that may be kept as pets—show potential for serving as animal models of human infection, but dogs, pigs, chickens, and ducks do not. And, although molecular modeling and in vitro studies suggest that multiple animal species may theoretically be able to be infected with SARS-CoV-2, a definitive intermediate host has not been identified. There is little to no evidence that domestic animals are easily infected with SARS-CoV-2 under natural conditions and no evidence to date that they transmit the virus to people. The primary mode of transmission of COVID-19 in humans is person-to-person spread.
Then in June, a major outbreak of SARS-CoV-2 infections occurred among minks farmed for their pelts in the Netherlands. To stop the spread, authorities gassed tens of thousands of minks But it was apparently too late.
Now, this is where the preprint, I mentioned in the first paragraph comes in. The researchers conclude that people gave SARS-CoV-2 to minks, but then minks gave it back to people.
Why is this significant? In the authors own words (emphasis mine):
To the best of our knowledge, these are the first animal to human SARS-CoV-2 transmission events documented. More research in minks and other mustelid species, to demonstrate if these species can be a true reservoir of SARS-CoV-2 although from our observations we consider this likely.
What we have now is strong evidence that SARS-CoV-2 will probably never be eradicated.
COVID-19 vaccine news
The good
While Moderna’s RNA vaccine and the University of Oxford/AstraZeneca non-replicating adenovirus vector vaccine have been getting the most press and are among the furthest along, a few other notable candidate vaccines have entered Phase III in which they will be tested in a large number of people. This is unequivocally good news.
Pfizer/BioNTech have expanded their Phase III RNA vaccine trials to 44,000 people. Expanding the trial will make it easier for the company to test the safety and effectiveness of the vaccine across a broader population.
Janssen Pharmaceutical Companies of Johnson & Johnson has an investigational adenovirus vector vaccine vaccine developed with a team at Harvard University that entered Phase III trials. This is a very promising vaccine because it had some stellar results in preclinical animal studies published in Nature. Also as NIAID Director Anthony Fauci noted:
“The Janssen candidate has showed promise in early-stage testing and may be especially useful in controlling the pandemic if shown to be protective after a single dose.”
This is one of the most promising candidate vaccines. This trial is enrolling up to 60,000 people. A single-dose effective vaccine with reasonable manufacturing processes and limited cold chain management would be awesome. India’s very own Biological E is slated to manufacture this vaccine so it should be available in India.
Last, but certainly not least, Novavax has gone into Phase III trials with a protein vaccine. Novavax has a tie-up with Serum Institute of India to produce this vaccine and according to some experts a protein vaccine might actually have fewer reactions that an RNA or viral vector vaccine.
The bad
Clinical trails have not started in children, so we don't know if the vaccines being developed are safe and effective in kids. And we probably won't know for a while, so broad vaccination by the end of 2021 in the best-case scenario may be a pipe dream. Some experts are of the opinion that the RNA and adenovirus vector vaccines that are leading the race might be reactive in children.
Given the number and proportion of children in any given population and their role in transmission, broader control of SARS-CoV-2 spread won’t happen until we have a vaccine that works in kids. And though (thankfully) children don’t usually get very sick due to infection, some do suffer from inflammatory and immune conditions that are serious.
The ugly
This. Is. Horrible. I won’t even link it because it is so wrong and yet has been shared by so many people.
Viruses are always mutating. That’s one of the things that make them viruses. I’ll have an explainer one of these days, but suffice it to say that the virus is not mutating to “bypass mask-wearing, handwashing.” Viruses don’t do that sort of thing.
What else I’m reading this week:
On the origin of mud.
Mud is awesome and everywhere. Apparently, this was not always the case. Land plants gave us mud and also changed the course of rivers.
The expansion of land plants between about 458 million and 359 million years ago coincides with a more than tenfold increase in mud on land — and a significant shift in the ways that rivers flowed.
A city in Brazil might’ve reached herd immunity for the coronavirus.
Researchers found that Manaus, a city in Brazil likely has the highest estimate of infections in the world at up to 66% of the population based on antibodies. In that city, SARS-CoV-2 has a predicted infection fatality rate of 0.28%. The reason this is such a significant study is because it represents the first natural example of possible herd immunity being reached anywhere in the world. In Manaus, the virus is running out of people to infect.
Human evolution is more complicated than we ever knew.
Today there is only one species of humans- the species that we collectively belong to. But even 300,000 years ago in Africa, there were other types of human-like species. What happened to them? Why did only Homo sapiens survive?
What is already abundantly clear is that human evolution was far more complex than previously appreciated by anthropologists. It was not a streamlined process of australopiths steadily evolving into modern humans, but a messy and haphazard journey that includes interwoven ancestries of many groups, some of which have never been discovered other than through the genetic traces they left in ancient and modern genomes.
The pre-order link for the hardcover “COVID-19: Separating Fact from Fiction” is now available on Amazon’s Indian site.
That’s it for this week. If you like this post, please share it.
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I was wondering whether children will be able to go back to school in 2021. It doesn't look like it.