Quantcast
Environmental News for a Healthier Planet and Life

Help Support EcoWatch

Can You Get the COVID-19 Coronavirus Twice?

Health + Wellness
A woman takes her temperature to check if she has a fever. Sam Edwards / Getty Images

By Sanjaya Senanayake

Governments are starting to lift restrictions and some are considering "immunity passports," where all restrictions are lifted for those previously infected.

But are you immune from COVID-19 if you've already been infected?


Some infections never recur once you've had them, such as measles and smallpox. But you can get plenty of others again, such as influenza and tetanus.

So far, research suggests at least a proportion of people who have had COVID-19 will be protected from another infection – at least initially. But the science is far from certain. Here's what we know so far.

First, a Quick Recap About Antibodies

When we encounter an infection for the first time, our body needs to respond quickly to the threat. So within hours, it activates our innate immune system. This system is quick-acting but isn't targeted to the specific threat.

The innate immune system's attack distracts the infection while the body produces a more targeted but slower response against the infection, via the adaptive immune system.

The adaptive immune system produces antibodies to fight the infection. These are what we measure in the blood when trying to determine who has been exposed to SARS-CoV-2, the virus that causes COVID-19.

The body produces different types of antibodies to respond to different parts of the virus. But only some have the ability to stop the virus entering cells. These are called "neutralizing antibodies."

According to the World Health Organization, people who recover from COVID-19 develop antibodies in their blood. But some people appear to have low levels of neutralizing antibodies.

To see if an antibody is a neutralizing antibody, you need to do special laboratory tests to see the effect of the antibody in cells exposed to the virus.

But even if an antibody blood test could confirm neutralizing antibodies, it doesn't automatically mean the person is immune from further infection. Even though the antibody is present, for example, the quantities may be insufficient to work.

So a positive antibody blood test to COVID-19 doesn't confirm if someone is immune to COVID-19 or not. It only tells us if a person has ever been exposed to COVID-19 – and even that depends on how sensitive and specific the antibody test is.

Why Do Some People Test Positive Again?

There are reports from different countries of people hospitalized with COVID-19 who tested negative when they were discharged, before testing positive again.

However, a study from China found those who retested positive didn't get any sicker. This suggests these people were intermittently shedding the virus and were at the tail end of their original illness, rather than getting a new COVID-19 infection.

The nasal and throat swab test being used to detect the virus also can't say whether the virus is alive or not; therefore, they could have just been shedding dead virus. This could explain why their close contacts didn't become sick or test positive.

Do Other Coronaviruses Generate Immunity?

Four other types of human coronaviruses (HCoVs) – 229E, NL63, OC43 and HKU1 – cause about 15-30% of the common colds worldwide. Two of these – OC43 and HKU1 – are a subgroup of coronaviruses known as betacoronaviruses, as are SARS-CoV, MERS and SARS-CoV-2.

A study from 1990 found infection with human coronavirus 229E generated protective immunity from that particular virus. But one year later, as antibody levels declined, these people could be reinfected. The researchers hypothesized a cyclic pattern of infection, with people getting coronavirus infections every two to three years.

More recently, when researchers examined 128 samples from people who had recovered from SARS (severe acute respiratory syndrome, or SARS-CoV), they found 90% had strong neutralizing antibodies, while 50% had positive T cell responses, meaning they were likely to be immune.

Given this information about other coronaviruses, it's likely that infection with SARS-CoV-2 provides some immunity from a second infection. But whether everyone becomes immune, and the duration of that immunity, are unknown.

Do Other Coronaviruses Provide Cross-Immunity Against COVID-19?

Cross-immunity is where immunity against one infection provides protection from another infection.

In one study, researchers tracked newborns up to 20 months of age. They found that infection with human coronavirus OC43 generated neutralizing antibodies that may have protected against HKU1. In other words, it led to cross-immunity.

If there is cross-immunity between HCoV-OC43 and HCoV-HKU1, which are both betacoronaviruses, it's possible they could generate cross-immunity with the new betacoronavirus, SARS-CoV-2.

But unfortunately, the current tests for COVID-19 (nasal and throat swabs, and blood tests) can't give us information about cross-immunity.

Why Could Cross-Immunity Be Important?

Cross-immunity with the other two betacoronaviruses could partly explain some of the inconsistencies we see with COVID-19.

For example, why do some people under 50 years of age experience severe and even fatal illness with COVID-19, while others over 100 years old fully recover?

Given that immunity to these two other betacoronaviruses is widespread and probably fluctuates over time, people with COVID-19 may have had different antibody levels against HCoV-OC43 and HCoV-HKU1 when they were infected with SARS-CoV-2. This could have contributed to differing levels of severity of COVID-19 infection.

It's even possible that the presence of cross-immunity could have been harmful rather than protective, because it might lead to an over-exuberant immune response. This phenomenon can be seen in dengue, another viral infection.

Over time, the issue of immunity to COVID-19 will be resolved. But for now, scientists are still piecing the information together.


Sanjaya Senanayake is an Associate Professor of Medicine, Infectious Diseases Physician at Australian National University.

Disclosure statement: Sanjaya Senanayake does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

Reposted with permission from The Conversation.

EcoWatch Daily Newsletter

Pexels

By Brian J. Love and Julie Rieland

The COVID-19 pandemic has disrupted the U.S. recycling industry. Waste sources, quantities and destinations are all in flux, and shutdowns have devastated an industry that was already struggling.

Read More Show Less
Pixabay

By Kris Gunnars, BSc

Unhealthy foods play a primary role in many people gaining weight and developing chronic health conditions, more now than ever before.

Read More Show Less
A man pushes his mother in a wheelchair down Ocean Drive in South Beach, Miami on May 19, 2020, amid the novel coronavirus pandemic. CHANDAN KHANNA / AFP via Getty Images

The U.S. reported more than 55,000 new coronavirus cases on Thursday, in a sign that the outbreak is not letting up as the Fourth of July weekend kicks off.

Read More Show Less
To better understand how people influence the overall health of dolphins, Oklahoma State University's Unmanned Systems Research Institute is developing a drone to collect samples from the spray that comes from their blowholes. Ken Y. / CC by 2.0

By Jason Bruck

Human actions have taken a steep toll on whales and dolphins. Some studies estimate that small whale abundance, which includes dolphins, has fallen 87% since 1980 and thousands of whales die from rope entanglement annually. But humans also cause less obvious harm. Researchers have found changes in the stress levels, reproductive health and respiratory health of these animals, but this valuable data is extremely hard to collect.

Read More Show Less

Sunscreen pollution is accelerating the demise of coral reefs globally by causing permanent DNA damage to coral. gonzalo martinez / iStock / Getty Images Plus

On July 29, Florida Governor Ron DeSantis signed into law a controversial bill prohibiting local governments from banning certain types of sunscreens.

Read More Show Less
Oat milk is popping up at coffee shops and grocery stores alike, quickly becoming one of the trendiest plant-based milks. jacqueline / CC by 2.0

By Kelli McGrane

Oat milk is popping up at coffee shops and grocery stores alike, quickly becoming one of the trendiest plant-based milks.

Read More Show Less

Trending


"Emissions from pyrotechnic displays are composed of numerous organic compounds as well as metals," a new study reports. Nodar Chernishev / EyeEm / Getty Images

Fireworks have taken a lot of heat recently. In South Dakota, fire experts have said President Trump's plan to hold a fireworks show is dangerous and public health experts have criticized the lack of plans to enforce mask wearing or social distancing. Now, a new study shows that shooting off fireworks at home may expose you and your family to dangerous levels of lead, copper and other toxins.

Read More Show Less