Caution, when your love's got COVID and you just had it

We've all wondered it at some point over the past two years: If I just had COVID-19 and my partner tests positive a few weeks later, is it safe to spend time with them?

Given what we think we know about immunity, we might assume the answer to this question is a resounding yes.

But scientists say: It depends.

Safe if you infected them

One thing is clear: If you have infected your partner, it's safe to hang out with them even if you test negative for the virus, because you both have the same variant, said Adam Squires, a lecturer in the University of Bath's Department of Chemistry who studies aerosol transmission of the virus.

Almost all researchers agree that after recovering from a COVID-19 infection, you are probably protected from reinfection with that specific variant for at least a month. There are some exceptions to this rule, but they are very rare and difficult to track given the fact that many people continue testing positive weeks after their bout with the virus.

Reinfection: Not enough data to say it's safe

The answer becomes more complicated if there's reason to believe that your partner got COVID-19 somewhere else. Maybe they tested positive two weeks after you had recovered or they just returned from a long holiday. They could be infected with a different variant than the one that caused your infection. 

In a case like that, Squires said, the chances of your getting reinfected are probably low but added that it was impossible to say for certain.

"It is unlikely, as far as we know, that you will get it," Squires said, given that your infection was very recent. And, even if you did get reinfected, he added, your recent infection would protect you against severe disease.

Since the probability of getting reinfected is low but not impossible, Squires said, it makes sense to open a window and keep some distance while hanging out with your COVID-positive loved one. And he cautioned against going to meet immunocompromised relatives when your partner is still positive.

"We don't know enough to say you definitely can't get COVID from your roommate or partner enough to pass it on," he said.

How does immunity work?

Many factors influence a person's susceptibility to reinfection, from their vaccination status to whether they have been infected before. 

That means there isn't a "one size fits all" answer to the question of when a person's "natural immunity"  — immunity gained from an infection — will wear off.

When a person becomes infected with COVID-19, their body starts creating large amounts of antibodies in the form of Y-shaped proteins, which work to disarm the virus by latching on to it and preventing it from infecting more cells.

Meanwhile the body is also producing something called T-cells, which can attack infected cells before they cause a full-blown case of the virus, and B-cells, which retain a memory of the virus and also help prevent full-blown infection when the body is confronted with the virus. These cells together form what we consider "immunity."

BA.4 and BA.5 infection

As we have observed time and time again over the course of this pandemic, reinfection is certainly possible, but typically takes a few months.

New variants, such as BA.4 and 5, are better at evading our immunity than past COVID-19 strains, but research shows that, although they're good, they're probably not good enough to "rapidly reinfect" people, as some news reports have claimed.

Some of the most conclusive research yet shows that if you were infected with a variant before omicron, like delta or the original coronavirus strain in early 2020, you probably are not well protected against infection with BA.4 and 5.

New variants cloud the picture

Unfortunately, we don't live in a simple world in which we can be certain the only variants worth taking into account are BA.4 and 5.

Although providing some logistical support to your partner is probably okay, "as for just 'hanging out,' I wouldn't advise it," said Mercedes Carnethon, a professor at Northwestern University's Department of Preventive Medicine in the US. "Multiple variants are circulating at one time in a community."

Along with BA.5 and BA.4, which are circulating in the United States and Europe, there's currently another variant circulating at lower levels: BA.2.75. Scientists don't know a lot about it, but the World Health Organization has listed it as a variant of interest.

Initial inquiries into its epidemiology show that BA.2.75 is better than other variants at infecting human cells and has mutations that may make our antibodies less able to bind to or neutralize the virus, Matthew Binnicker, director of the Clinical Virology Laboratory at the Mayo Clinic in the US, said in a press briefing in late July.

"There is some concern that this virus may be able to spread quicker and also be able to evade immunity from vaccination or prior infection," Binnicker said.

What does all this mean?

Don't panic! If you recently tested positive and your partner tests positive a few weeks later, your chances of developing COVID-19 a second time are probably pretty small — not impossible, but unlikely. Doctors encourage you to stay cautious, wear a mask in public and abstain from seeing immunocompromised family members if you do choose to spend time with your infected sweetie.

If it's been more than a month since your positive infection, at which point your immunity could begin to wear off, it's probably better to distance from each other, given the chance of reinfection with a new variant.