Covid-19 may be here to stay, according to an article from nature.
How and why? These questions will be answered in this summary.
Disclaimer: SARS-CoV-2 is technically still classified as a pandemic by scientists due to many people still being susceptible to it. If it were to become an endemic, the number of infections would become relatively stable across years (with occasional flare-ups).
The Endemic Future and the Opinion of Scientists
In a few countries the people in some regions were able to enjoy a life free of SARS-CoV-2, and in this case Western Australia. This was achieved by placing heavy restrictions on travel and imposing lockdowns. Naturally, the following question arises:
„If other regions, aided by vaccines, aimed for a similar zero-COVID strategy, then could the world hope to rid itself of the virus?“
While it may sound achievable to a layman, most scientists think that it is improbable.
Nature asked in January 100 immunologists, infectious disease researchers and virologists who work on the coronavirus whether it could be eradicated. These are the results:
89% think it is likely that it will become an endemic
6% think it is unlikely.
6% think there’s not enough evidence to estimate
39% think that SARS-CoV-2 can be eliminated from some regions
52% think it is unlikely
10% think there’s not enough evidence to estimate
Note: „Percentages do not add up to 100% because of rounding.“
The failure of eradicating the disease doesn’t mean that death, illness or social isolation will continue on the scale we have seen so far. It depends on the type of immunity we acquire through vaccination and how the virus evolves.
Influenza and the four known coronavirus which cause common colds are endemic as well.
In other words: „[…] a combination of annual vaccines and acquired immunity means that societies tolerate the seasonal deaths and illnesses they bring without requiring lockdowns, masks and social distancing.“
In regions with zero-Covid, there’d still be a risk of new outbreaks, but those could quickly be eliminated by herd immunity if most people had been vaccinated.
It doesn’t sound like there’s much certainty which way the virus will go. Angela Rasmussen, a virologist from Georgetown University, said: “The virus becoming endemic is likely, but the pattern that it will take is hard to predict.“
The graphic below explains how it could become an epidemic:
Once a immunity is reached – natural or through vaccination – , though, the people won’t experience severe symptoms. In fact, if the virus sticks around, it would become a childhood virus encountered early when growing up – that means that there are typically mild infections or none at all (according to Jennie Lavine, an infectious-disease researcher at Emory University in Atlanta, Georgia).
It is considered possible, because of the behaviour of the four other endemic coronaviruses known as OC43, 229E, NL63 and HKU1 – three of them have probably been circulating in human population for hundreds of year; and two of them are responsible for 15% of respiratory infections.
Regarding Covid-19, memory B-cells were made by people who had caught the disease.
This means that, even though the antibodies decline after 6 months, new antibodies can be manufactured as soon as the individual is being re-infected with the virus. The T-cells will then eliminate the infected cells – as it normally does with known infectious diseases.
However, the article continues: „It’s yet to be established if this immune memory can block viral reinfection — although cases of reinfection have been recorded, and new viral variants might make them more likely, they are still considered rare.“
Weiskopfs says that, if the majority of the people develop a life-long immunity to the virus, then it is unlikely that the virus will become an epidemic. The acquired immunity might wane after a year or two, especially when the virus is able to evolve and escape.
„More than half the scientists who responded to Nature’s survey think waning immunity will be one of the main drivers of the virus becoming endemic.“
Until a steady epidemic is reached, it could take a few years or decades. It also depends on how quickly populations develop immunity. And while allowing the virus to spread unchecked would be the fastest way to get to the point, Lavine says, it would also result in millions of deaths. Consequently, the path through vaccination is the safer and option.
Vaccines and Herd Immunity
Vaccines that prevent symptomatic infection might also stop transmission from one person to another, as clinical trials have suggested. In case of a successful block of transmissions, there’s the possibility of eliminating it in some regions as long as enough people are vaccinated which in turn also protects those who are not vaccinated, thus contributing to herd immunity.
- Vaccine with 90% effectiveness:
At least 55% of the population needed to achieve temporary herd immunity, but some social distancing measures have to be kept (like face masks and home office) according to a model from a model that was developed by Alexandra Hogan at Imperial College London and her colleagues
- If a vaccine is less effective than 90% or a new more infectious variant arises, vaccine coverage needs to be greater to weaken the circulation
Vaccinations requires the willingness of the people to get vaccinated, and a survey written about in the article shows the worrying aspect:
„A survey of more than 1,600 US citizens found that more than one-quarter (25%) would definitely or probably decline a COVID-19 vaccine, even if it were free and deemed safe (see go.nature.com/3a9b44s). “How successful we are at addressing those concerns will determine how many people get the vaccine and how many remain susceptible,” says Rasmussen.“
Insufficient immunization could lead to a similar outbreak of measles, which is an endemic in some parts of the world: „In 2018, a global resurgence killed more than 140,000 people.“
Animal reservoirs will also decide whether it becomes an epidemic (i.e. SARS-CoV-2 success in wild animal populations), some diseases have shown to be persistent because of that. Among them are yellow fever, Ebola and chikungunya virus.
From the views of the scientists and the history of other coronaviruses and influenza, as well as factors such as vaccination effectiveness and virus mutation, we therefore also come to the conclusion that it is likely to become an epidemic.
While we may have to live it, we can ensure that all nations receive the vaccines to combat the disease effectively and get with cooperation future outbreaks also under control.
Moreover, disinformation must be fiercely combatted to ensure that there are no larger outbreaks of SARS-CoV-2 in the future or other illnesses.
Extra: SARS-CoV-2 is of Natural Origin
In an article around April 2020, I already wrote about the origin of the novel coronavirus. No country engineered it, and here are the facts from back then:
- The RBD portion of the SARS-CoV-2 spike proteins had evolved to effectively target a molecular feature on the outside of human cells called ACE2, a receptor involved in regulating blood pressure. The spike proteins of Covid-19 were even so effective at binding the human cells, that the scientists concluded it was the result of natural selection and not the end-product of genetic engineering.
- „If someone were seeking to engineer a new coronavirus as a pathogen, they would have constructed it from the backbone of a virus known to cause illness.“ However, the backbone of SARS-CoV-2 differed substantially from those of already known Coronaviruses. It also mostly similar to other viruses found in bats and pangolins.
The article, from ScienceDaily, also pointed out the role of animals:
„If the SARS-CoV-2 entered humans in its current pathogenic form from an animal source, it raises the probability of future outbreaks, as the illness-causing strain of the virus could still be circulating in the animal population and might once again jump into humans. The chances are lower of a non-pathogenic coronavirus entering the human population and then evolving properties similar to SARS-CoV-2.„
I hope I was able to inform you well, but I still recommend to read the original article of nature which elaborates more on it and also mentions aspects I have cut out to make this a summary.