The European Union drug regulator gave its backing Tuesday to mixing different types of vaccines in initial vaccination and booster campaigns to battle the coronavirus.

The European Medicines Agency said in a statement that using different types of vaccines together, known as heterologous vaccination, can provide protection against COVID-19.

The announcement comes as much of Europe is facing rising infection and hospital rates and concerns about the new omicron variant.

The EMA, together with the European Center for Disease Control, said that a mix-and-match strategy could give nations more options in vaccination campaigns as much of the continent seeks to contain the latest surge in the pandemic.

“The evidence available so far with different types of authorized vaccines indicates that a heterologous booster appears as good as or better in terms of immune responses than a homologous booster,” the agencies said in a statement.

“While research is ongoing to provide more evidence on long-term safety, duration of immunity and effectiveness, the use of heterologous schedules may offer flexibility in terms of vaccination options, particularly to reduce the impact on the vaccine rollout should a vaccine not be available for any reason,” they added.

The agencies looked at data for mRNA vaccines like the Pfizer shot and so-called viral vector vaccines such as the one made by Johnson & Johnson. The two types of vaccines use different technologies to spur the body to fight the coronavirus.

U.S. and U.K. authorities have already given the green light to mixing and matching vaccines in booster campaigns.