We are close to the two-year anniversary of the COVID-19 pandemic. Over 5 million people have died around the world, and that is almost certainly an undercount, especially in countries that don't have the resources to properly test and vaccine their populations. We have seen four surge cases since early 2020, hoping that each would be the last. Last week, scientists detected a new variant of Omicron-sars-cov-2-variant-of-concern, which may lead to another rush of cases or have no lasting effects. We don't know enough to tell.
Everyone is ready for the Pandemic to be over, but it is not clear what it will look like. How likely is it that the virus will be eradicated? What will the world look like if we can't?
We have learned enough to answer some of the questions we have about the virus that causes COVID-19.
A column where top researchers discuss the process of discovery. Tara C. Smith is a professor of epidemiology and infectious-disease researcher.
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Can we stop COVID-19?
Some people think so. The high costs of an endemic SARS-CoV-2 virus are cited by advocates of a campaign to eradicate it. Over 250 million infections have been confirmed globally with over 5 million deaths, and economists have estimated that COVID-19 would cost the U.S. over a trillion dollars by the year 2030. COVID-19 will be expensive on multiple fronts even with the vaccines.
It is true that once a pathogen is eliminated, there can be reduced or eliminated measures. The general public no longer gets a vaccine for smallpox, though we still maintain a military program. One medical journal said that eradication of the disease should not be ruled out, and that it could be just as challenging as the eradication of the disease of the same name.
I don't agree. eradication is unlikely because of the epidemiology of the virus. Investing in a campaign would be misuse of limited resources and the failure of a high-profile eradication campaign could make other levels of control more difficult.
What is the difference between eradication, extinction and elimination of a virus?
Eradication means that the virus is gone. We have achieved this with rinderpest in animals. The destruction of any samples in laboratory stocks is included in Extinction. This has not yet happened for any pathogen, for many reasons that are mostly political, such as the distrust between the U.S. and Russia, who each hold remaining stocks of the virus.
Elimination is sometimes confused with eradication. Eliminating new infections within specific countries is a more limited form of control than eradication. In the US, we have done this with other viruses, including the ones that cause the diseases. While we have had recent outbreaks of the disease, the original cases came from travelers who were exposed to the disease abroad.
It is difficult to maintain elimination. The U.S., which eliminated the disease, almost lost that status due to the outbreak of the disease in 2019.
What makes COVID-19 so resistant to eradication?
An effective intervention that can stop transmission, readily available diagnostic tools that can quickly detect infections, and a lack of the disease among nonhuman animals are some of the qualities that a candidate for eradication will possess. COVID-19 fails on all three counts.
We think that a lot of the COVID-19 infections are not life threatening. Control of spread and diagnosis is complicated by that. Many other infections have almost certainly occurred that went unrecognized. To find them, we would need to build up a lot of programs to look for them, as we did in the campaign to eradicate polio. If you don't know the disease is there, it's hard to interrupt transmission.
It is difficult for a diagnosis for a symptom. The symptoms of COVID-19 are similar to those of influenza and other respiratory viruses, meaning rapid, accurate, widespread and affordable testing is critical to confirm cases.
There is no end in sight to the disease that is currently circulating among multiple species of animals.
What do other animals do?
Smallpox, measles and the like are caused by human-specific viruses, so they are easier targets for eradication. The zoonotic pathogen that originated from a bat is known as SARS-CoV-2. There is a nonhuman virus in nature. Researchers have found the disease in many other animal species, including ferrets, otter, white-tailed deer, and gorillas.
There are always sources of the virus that could be reintroduced into humans. It only takes a single event to bring the virus back into an area where it has been eliminated. If eradication or elimination is the long-term goal, each new chain of transmission needs to be stopped.
What about vaccines?
The current vaccines for COVID-19 aren't as effective as the vaccines for smallpox, measles and polio are. If people are vaccine-vaccinated, they can reduce transmission, but not eliminate it. This makes eradication more difficult.
There is an additional issue. The vaccines that cause the diseases can generally cause less genetic diversity in the viruses. It is possible that a variant of the disease will escape the immunity brought on by previous infections, but we are not sure how much of an impact it will have. The Omicron variant is being tested to see if it can escape from the antibodies generated by prior versions. The immune system recognizes the spike protein as the key to binding to the host's cells. If the changes hit in the right places, they could alter theProtein to such a degree that our antibodies will bind to it less tightly or no longer recognize it.
The issue of immunity is waning over time. Long-term immunity can be achieved by vaccination for diseases such as tetanus, diphtheria, and encephalitis. Individuals are susceptible to reinfection with coronaviruses because immunity can rapidly decline. This is already happening with both vaccine and previously infections.
The solution to these issues is simply additional vaccinations, but that requires a regular, global vaccine campaign that would have to surpass vaccination efforts in 2021, which themselves only came about with emergency funding and have still left many unvaccinated, either because they declined the vaccine or because it's not
There are other reasons to be skeptical.
The eradication potential is only one aspect of the issue. Political and economic considerations are more difficult.
Eradication is a global enterprise. Eradication is not only possible but necessary, and interventions must be accessible and affordable. The World Health Assembly is the World Health Organization's decision-making body. It is here that any campaign must begin, as delegates are the first to decide if eradication is feasible, if it is a good use of resources, if all countries value it enough to contribute, and so on. Logistical issues would delay and hinder the project even if everyone was interested in working toward the goal.
What should we do?
We have other options that are unlikely to be eradicated. It is possible to eliminate infections within defined geographic areas, but it would take many years of sustained work. It is unclear if any coronaviruses vaccine can provide long-term immunity and better protection from breakthrough infections, given that even an infection does not.
We must aim for control in the short term, because of the loftier goal of elimination. This will come at a higher cost than many public health experts are comfortable with, of thousands of COVID-19 deaths each year and additional chronic outcomes, such as long COVID. Over time, the combination of vaccination, infection-inducing immunity and novel treatments should reduce the risk of serious infections and death from COVID. It is possible to keep immunity high and respond to any variations in circulating virus with an annual vaccine. Some people may choose to wear masks in times of increased infections.
We need to be clear about what to expect. With interventions, the specter of COVID-19 can be defeated. It is unlikely that this will herald the return to normal that so many desperately desire.
