As hospitals worldwide are inundated with highly infectious coronavirus victims, knowing who is immune, and who is not, could be a powerful weapon in identifying healthcare workers best able to provide support, not to mention regular workers who are able to re-enter the economy, experts say.
The scientific community still does not know how long natural immunity to coronavirus – one that is developed from contracting COVID-19 and surviving – may last. But testing for immunity – as opposed to infection – has already begun in parts of Asia and could soon become vital for the rest of the world.
“We can’t know how long natural immunity would last, but we have reason to suppose based on prior coronaviruses that it will be sustained,” Dr. Nicholas Christakis, a physician and professor of social and natural science at Yale University told Al Arabiya English.
Let’s talk about what happens if you get COVID19 and recover. Are you immune to the disease? How long does the immunity last? And what does that mean for your life and for the public health and economy of our society? 1/— Nicholas A. Christakis (@NAChristakis) March 19, 2020
To test for immunity requires a blood test to detect the presences of antibodies, which tell if a person has ever been infected. Singapore, China and a few other countries have begun antibody testing, but the tests are not currently widely available. In Singapore, a group at Duke-NUS Medical School developed a serological test, a test that measures body serums, but they are awaiting validation before it can be produced widely, Science magazine reported last month.
Right now the focus for many countries in Europe and North America is testing for the coronavirus infection, but for countries in Asia that have already seen infections peak, the focus is shifting to immunity.
Without a vaccine, which most experts say is one to two years away from being market ready, testing for this immunization could be key to getting economies back on track and could also benefit struggling health care systems.
Restarting the economy
“It’s to my benefit for you to be tested and shown to be immune, because you can go out and drive a cab, or go to a restaurant and wait tables, or be a teller at a bank,” Christakis said. “It’s to all of our advantage to know if you’re immune.”
Most people who contract the novel coronavirus show mild to no symptoms and may even be unaware they are infected. Now, because of the surge in infections and accompanying lockdowns, those people despite their immunity, are stuck at home.
“If you can tell who’s immune and who’s not immune, then people don’t have to stay at home, and they can go about their business,” Christakis said. “This is crucial to getting our economies going again.”
Lockdowns imposed to slow the spread of the virus have triggered a massive drop in economic activity, putting millions of people out of work.
The United States on Friday approved a $2.2 trillion stimulus bill to refloat the economy, while Gulf Cooperation Council economies have announced more than $120 billion of stimulus spending to counter the effects of the lockdown.
Health workers in hazmat suits are seen at the gate of Vietnam's largest hospital, Bach Mai, where coronavirus cases have been detected in Hanoi, Vietnam March. (File photo: Reuters)
Health care workers who are on the frontline in the fight against coronavirus found to be immune could more safely take care of highly infectious patients. For months, hospitals have faced shortages of protective equipment like masks and gloves and many are overwhelmed by the volume of patients.
Immunity to other viral infections vary
Other viral infections, like the flu and other coronaviruses, have varying time periods in which a person is immune, and what is known about past coronaviruses, like SARS, may or may not be applicable to COVID-19.
“We find serologic – like a blood test – evidence of immunity for up to a year for SARS, but we think you’re still immune in a different way for a longer time,” explained Christakis.
Other viral infections, like the common cold, induce an immunity for around three months, Dr. Maher Balkis, associate staff physician for infectious diseases at Cleveland Clinic Abu Dhabi told Al Arabiya English.
For the flu, a vaccine is needed annually because the immunity created only lasts a year, explained Christakis.
A lot of unknowns
Experts say there is reason for optimism of sustained immunity against COVID-19, and preliminary testing on monkeys may be one indicator of immunity, but it’s also too early to know for sure how long a recovered person will be immune.
“A preliminary study in China that looked at the virus in macaque monkeys has found that some recoveries may induce an immunity to re-infection. However, we do not know how long that immunity might last,” Balkis said.
Balkis also said there have been anecdotal reports of recovered patients becoming re-infected, but the details are unknown as to whether they had fully recovered before re-testing positively. He added there is always a possibility for a false negative test.
“As we continue to study this novel coronavirus, we will learn more about how it works, how it can be treated and how long any immunity might last,” Balkis said. “For the moment, it is vital that people continue to practice social distancing, stay at home as much as possible, and practice proper hand hygiene.”
Vaccines are one of the surest ways to protect a population from mass infection, the other being herd immunity, which occurs when a high percentage of a community is immune to a disease through vaccination or prior illness, making the spread of the disease from person to person unlikely. Vaccine development efforts are under way in several labs around the world, but one study found that on average vaccines take 16 years to develop and cost around $1 billion to develop in the US. Many experts expect a coronavirus vaccine to be developed within a year or two.
The immunity provided by previous infection to a virus is stronger than that introduced by a vaccine, experts said.
“[In a vaccine,] we give you a part of the pathogen that can’t harm you, but then your body mounts a defense against, that way when you counter the real pathogen you fight it more effectively,” Christakis said.
But when a person contracts a disease and survives, “your body mounts a very broad defense against, many parts of it, not just what might be in a vaccine, and that’s a more sustained immune response,” he said.
Herd immunity has been hotly debated as a strategy in the UK. Prime Minister Boris Johnson, himself infected with the virus, had advised against imposing draconian restrictions on movement earlier in March, arguing that herd immunity would be the best protection for people long term. The UK has since introduced a total lockdown.
“This pathogen is going to become endemic, or like the flu,” said Christiakis. “It’s just going to circulate around the planet and infect us. Eventually, we’ll develop immunity. This is why the British strategy was not completely irrational, but what we’re trying to do here [with social distancing measures], we’re trying to convert a tsunami into a slow rolling tide. The same amount of water will still wash ashore, but it will wash ashore more slowly so we can get ready for it.”
Christakis said now the need is to develop good antibody tests, expedite necessary approvals, and produce enough testing kits for widespread application.SHOW MORE