Although there isn’t much data on the fourth dose, infectious disease experts suspect that mixing up your second booster will be similarly beneficial.

While there may be a slight edge to mixing vaccines, you’ll still be well protected against severe outcomes if you decide to stick with the same type of shot for your second booster, according to infectious diseases experts.

The one caveat is that anyone who initially got the Johnson & Johnson vaccine will want to follow up with one of the messenger RNA (mRNA) vaccines like Pfizer or Moderna as evidence consistently shows they provide stronger protection.

The data is limited on how mixing vaccines for your fourth dose specifically impacts protection, but prior research shows that the mix-and-match strategy with the first three doses provided a broader immune response.

“I think that there is evidence that mixing and matching between the mRNA vaccines may have some benefit because they slightly stimulate the immune system in different ways,” said Amesh Adalja, an infectious diseases expert and senior scholar at the Johns Hopkins University Center for Health Security.

A study evaluating the effectiveness of the Pfizer and Moderna vaccines recently found that people who’ve received the Moderna shot had more antibodies within the mucus lining in the nose, which helps prevent infection.

At this point, though, experts say it’s fine to go for the other type of mRNA shot or stick with what you’ve had.