Can You Get Coronavirus Twice?

As the case count soars around the world, scientists and the general public are challenging the idea that an individual is immune to the virus once he or she has contracted it and recovered.

With California projecting a more than 50% infection rate in 6 to 8 weeks, it is crucial to our understanding of the disease that we firmly establish whether herd immunity will help mitigate future outbreaks.

What is Herd Immunity?

Herd immunity is the idea that, once a sufficient percentage of a population is immune to a pathogen, that pathogen will no longer spread within the population. Notably, the entire community need not be immune, just a high enough percentage for the virus to be unable to travel through the general public.

The percentage necessary to achieve herd immunity varies according to how contagious the disease is. The United Kingdom initially backed a herd immunity approach, telling citizens to essentially keep calm and carry on. Once the infection rate reached 70%, British scientists projected, COVID-19 would pose a substantially lower public health threat.

However, the country has since changed course, after scientists released daunting projections regarding deaths and hospitalizations if Britons did nothing in response to the virus.

Though the UK may be unique in its initial strategy, all countries are relying to some extent on the idea that, like most other viruses, humans are immune after exposure, illness, and recovery. This idea hinges on a key question.

Can you get coronavirus twice or does it cause immunity? https://t.co/q1JPhnn9Nu

— The Independent (@Independent) March 16, 2020

Can You Catch it Twice?

A definitive answer has yet to be given, but the emerging evidence, like much of the figures surrounding the virus, is torturously vague. The preliminary conclusion: maybe, but probably not.

The story of a Japanese woman catching the virus twice has been making its rounds, prompting speculation that humans may not develop a full immunity after suffering through and recovering from the virus.

The woman, a tour bus guide from Osaka, tested positive on January 29, recovered a few days later, and tested negative on February 6th. Then, a few weeks later, she tested positive for the virus again, experiencing moderate but more severe symptoms than the first exposure. Though this case is apparently unique as a reported double infection, it raises grave concerns for the prospect of developing some level of population immunity without a vaccine available.

Coronavirus, which is actually a family of pathogens and not a single disease, has been extensively studied in the past. SARS, which threatened a pandemic in the early 2000’s, was part of the same family.

The scientific community affirms that it is very rare to see a specific coronavirus infect the same host twice in the same year, though it has been seen in some bats. Some level of immunity will be seen for a couple of years, and the vaccine is expected in about a year.

The general conclusion is that, after recovering, one should continue to observe the same safety protocols, but rest assured that reinfection is highly unlikely.

Can You Get Coronavirus Twice? How Long Are You Immune After COVID-19? #Immunity #COVIDー19 #COVID19 https://t.co/5yvLL1l9kX

— Atanas G. Atanasov (@_atanas_) March 16, 2020

Herd Immunity Grows Ever More Relevant 

With confirmed infection rates still well below 1% for the United States and the rest of the world, herd immunity, which would theoretically require immunity rates of around 70% for COVID-19, seems a distant prospect.

However, projections for the rate of infection are now near this figure for a number of places, including California (56%) and Madrid (80%), in the weeks and months to come.

If we reach these rates, however, the concern is not likely to be one of repeated infection, but how to weather the overwhelming effect on the healthcare system. For this reason, scientists stress the importance of reducing our interaction with others, rather than relying on future immunity.