Early research suggests your risk of getting COVID in the next wave is lower if you already had Omicron. Here's everything we know about BA.2 reinfections.

At this point, a lot of people have already experienced Omicron and now BA.2, an extra contagious sub-variant of Omicron, is traveling the globe.

In Europe and the northeastern US, BA.2 has taken over, making it the dominant version of the Omicron variant.

There has been a noticeable increase in infections with BA.2 across Europe this spring.

Many people who have been exposed to Omicron in recent months are wondering if they can get it again.

The answer is probably not.

This is what we know so far.

Reinfection with Omicron is possible, but not common

In other places around the globe, there are lots of COVID-19 cases, but it is rare for them to re-invade with BA.2 after BA.1.

They looked at data from more than one million cases in a three month period between November 2021. The researchers wrote that most of those were young, unvaccinated individuals. In England, among more than 500,000 BA.1 and BA.2 samples taken between November and February, just 43 potential reinfections were discovered.

It is worth noting that the studies were done in a short period of time. It is not known how long Omicron immunity will last, and how well it works for everyone.

Some lab studies done with blood samples found BA.1 infections provide decent cross-protection against BA.2 

A letter posted in the New England Journal of Medicine on March 16 evaluated blood samples from 24 vaccine recipients and boosted the number of people who had never had Covid before.

The study suggested that.

• The people most vulnerable to BA.2 are the unvaccinated who were not infected with BA.1
• Booster shots appeared quite helpful to prop up antibody levels against both BA.1 and BA.2 for people who had never been infected
• The people with the best protection against BA.2 were people who were vaccinated, boosted, and previously infected
• On average, vaccinated people in the study who had a prior COVID-19 infection (presumably BA.1) had more than three times the level of neutralizing antibodies against BA.2 as anyone else did.

There is a substantial degree of cross-reactive natural immunity for BA.2 from BA.1, the researchers said.

Booster shots will likely work as well on BA.2 as they did on other versions of Omicron

The New England Journal of Medicine letter shows that booster shots work as well against BA.2 as they do against BA.1.

We have lots of data from the Omicron outbreak that peaked in January in the US and it shows that boosted individuals, even those without a prior infection, fare very well against bad outcomes with Omicron.

Now that more time has elapsed since people got their third shots, how fast is booster shot protection fading?

"Hybrid" immunity shows there are advantages to vaccinating or boosting people who've had COVID

A large preprint study, which relied on vaccination and infection data from the entire country of Qatar, was posted online Tuesday. It hasn't been peer-reviewed yet, but it suggests that the best protection against an Omicron infection is a prior infection plus a booster shot.

The study found that from late December to February.

• prior infection with COVID reduced the risk of infection with BA.2 by 46%
• vaccination plus a recent booster reduced the risk of infection by 52%
• so-called "hybrid" immunity (2-dose vaccination + prior infection) reduced the risk of infection by 55%
• "hybrid" immunity plus a recent booster reduced the risk of infection by 77% 
• two-dose Pfizer vaccination without a recent booster shot had a "negligible" effect on preventing Omicron infections, though those fully vaccinated patients were still well-shielded from severe disease, hospitalization, and death during the Omicron wave. (Pfizer's is the most commonly-used COVID vaccine in Qatar.)

The bottom line

There are plenty of vulnerable people who may not have caught BA.1, and who could suffer a dangerous outcome with the more infectious BA.2.

There is some data that suggests that a prior Omicron infection may provide some decent immunity against BA.2 Omicron.