Bengaluru: The World Health Organization (WHO) said this week that Covid-19 may not go away, and eventually become endemic like HIV.
“It is important to put this on the table: this virus may become just another endemic virus in our communities, and this virus may never go away. HIV has not gone away, but we have come to terms with the virus,” WHO emergencies expert Mike Ryan said in an online briefing.
“I don’t think anyone can predict when this disease will disappear. I think there are no promises in this and there are no dates. This disease may settle into a long problem, or it may not be.”
Weighing in on efforts by many countries to ease the lockdown, WHO Director General Tedros Adhanom Ghebreyesus said “the trajectory is in our hands… we should all contribute to stop this pandemic”.
“Many countries would like to get out of the different measures,” he added. “But our recommendation is still the alert at any country should be at the highest level possible.”
With the WHO warning, the writing is on the wall — we may never completely get rid of Covid-19, which has already killed over 3 lakh people around the world since it was first diagnosed in China in December 2019. So, would it mean a near-complete lockdown forever? Not quite, if we take other endemic diseases as precedent. ThePrint explains.
What are endemic diseases?
Endemic diseases are those where a virus or a pathogen keeps circulating in the human population, infecting people who haven’t been vaccinated.
The disease could be seasonal or occurring all year, and could be caused by a bacteria or virus or any other pathogen.
Common endemic diseases humans have learnt to live with include malaria, cholera, typhoid, tuberculosis, ebola, influenza, and HIV. These were all outbreaks at some point, but now occur around the year or seasonally, even resulting in fatalities.
There are even four endemic coronaviruses that cause the common cold. Humans can contract the common cold at any given point of time and infect others.
But none of them requires all human activities to come to a standstill, even at a local level, to be dealt with.
On the other hand, some coronaviruses associated with earlier outbreaks, like the Severe Acute Respiratory Syndrome (SARS) and the Middle-east Respiratory Syndrome (MERS), were contained before a functional vaccine could be developed and rolled out. This was possible only because the diseases they triggered caused violent illness.
A person infected with deadly viruses falls sick relatively rapidly, and is forced to stay at home, which mitigates the chances of transmission by diminishing the scope for physical contact with others.
For a virus to be successful, it has to infect a person just enough to cause a mild illness that doesn’t require a strong medical intervention and doesn’t evoke much worry at once.
Some diseases are extremely deadly and equally infectious, such as measles. Such diseases can only be stopped by vaccination. However, even though the MMR vaccine has helped control mumps, measles, and rubella for years, none of the three has been eradicated yet.
Case study for a Covid-19 future
There are viruses, with and without vaccinations, that could be looked at to understand how a Covid-19-endemic world will look like. One example is HIV, which doesn’t have a vaccination yet.
The Human Immunodeficiency Virus (HIV), which causes the lethal AIDS if not treated, is believed to have first entered the human population 100 years ago from chimpanzees in what is today the Democratic Republic of Congo. In the 1980s, HIV, which is transmitted through bodily fluids like semen and blood, became a pandemic.
By 1990, there were about 1.5 lakh official cases in over 145 countries, but the total estimate was thought to be closer to 4 lakh.
Today, we have antiretroviral drugs that can treat HIV even as a cure remains evasive. Nearly 20 million people are being treated for HIV, and proper treatment allows patients to live a relatively comfortable life as compared to the 1980s, when HIV infection was seen as a death sentence.
Malaria is another example of a zoonotic disease we haven’t managed to get rid of, and the world has been plagued by it for millennia. The earliest discovered evidence of the malaria parasite in mosquitoes dates back 100 million years.
Malaria in humans dates back at least 10,000 years. Evidence for this lies in the evolution of the bodies’ genetic response to malaria, such as the sickle cell disease.
Sickle cell disease, a form of anaemia, provides inherent immunity to malaria. It has been found to have wide incidence in regions where malaria is endemic, such as several parts of Africa.
Malaria has also killed millions of people, and continues to do so to this day. However, humans have learned to live with malaria to a large extent even in the absence of an effective vaccine. There is a malaria vaccine, developed in this decade, but it isn’t as efficient as vaccines should ideally be and is still undergoing further improvement and testing.
Endemic diseases tackled through vaccination
Small pox was another disease that existed in human beings for thousands of years, but it was declared eradicated by the WHO in 1979, at least a century after the vaccine became widely accepted.
Small pox is the only disease humans have officially completely eradicated through vaccination. Rinderpest is an example of a disease among animals that has been eradicated.
There are currently ongoing drives to eradicate polio and malaria, while measles and rubella have been identified as potentially eradicable.
The novel coronavirus is nowhere close to being eradicated at the moment. Humans don’t even have a semi-functional vaccine, and thus it is not even containable at this point, except through reduction of contact. Additionally, we don’t know how long our bodies’ immunity — whether from natural infection or through vaccination — would last.
However, the good news is that humans have never before collaborated at such a scale, working so fast. As the medical and scientific communities work hard to bring about vaccines and drugs to make our lives easier, humans have to figure out how to live with the virus, while preventing as many deaths as possible.