There is now good evidence that social distancing and other non-medical preventative strategies to contain COVID can work. In addition, new evidence suggests these measures also work to help prevent the spread of other infectious diseases, including some types of meningitis. But behind a short-term win of lower global non-COVID infections lurks a potential risk of ‘disease rebound’. The reduced exposure to viruses and bacteria linked to COVID prevention measures could lead to a lack of immunity in the population which opens corridors for diseases to spread rapidly. This could increase cases and mean new epidemics arise as social distancing measures are eased, as highlighted in a recent paper by the Paediatric Infectious Diseases Group (GPIP) based in France.

Focusing solely on the fight against COVID could create a ticking time bomb for public policy. There is an urgent need for public and policy education and awareness to explain the potential risks of new epidemics and ensure suitable action is taken before it’s too late. That time is now.

Three things really matter that everyone needs to know.

Firstly, before COVID, effective treatments and innovative vaccines had reduced the threat of many infectious diseases, but they had not gone away.

Exposure to bacteria and viruses can cause life-threatening infections, but while nearly all of us are exposed to meningitis-causing bacteria at some time in our lives, most of us do not become ill. Most people who are exposed instead go on to carry the bacteria in the back of the nose and throat for a period of time, and this can build or boost immunity. Some strains of the meningitis-causing bacteria Neisseria meningitidis (also known as meningococcal bacteria) are more likely to be harmlessly carried than others, and many of us are protected from developing meningococcal infection because we have carried a related, but harmless bacteria called Neisseria lactamica when we were young children. Carrying these bacteria contributes to the development of population-wide herd immunity and helps stop the spread of more serious and deadly forms of meningococcal bacteria.

Social distancing and other COVID responses have severely curtailed this natural circulation, blocking both the benefits and harms of exposure to these bacteria. We could see a lack of immune stimulation leading to an ‘immunity debt’ within the population. This in turn means people are less protected and even more reliant on vaccines than they would otherwise be. Once everyone starts meeting up again, more people are potentially at risk of infectious diseases that had previously been in decline. Low infection rates in the short-term could therefore lead to a rapid resurgence as lock-downs ease around the world.

Secondly, on top of the protective nature of some exposure to bacteria, lots of people have missed out on vaccines that offer protection. Some people were not attending routine vaccine appointments due to fear of attending medical facilities in the midst of a pandemic. Other vaccines were missed due to school closures or campaigns being cancelled as resources were distributed elsewhere. There is growing evidence of need for massive catch-up campaigns for vaccines that prevent infectious diseases to halt this alarming drop in protection.

Finally, governments the world over have seen their economies hit by COVID and will naturally feel responsible for stabilising their finances as lockdowns unwind. In this environment, a fall in infectious diseases could look like an easy win for cost savings to be made on vaccine programmes (outside of COVID).

This triple threat of reduced natural immunity combined with lower vaccination rates and economic expediency, all wrapped up in seemingly low levels of current infection, could be catastrophic if they are misunderstood.

Whilst it is true that disease rebound is not a certainty it is a very real risk. It is possible infections will stay low for some time. The work to model what could happen is progressing now. But that fact is, we do not and cannot know for certain what will happen. In this circumstance, the right response is therefore to use the tools we already have at our disposal and take unnecessary risk out of the picture altogether.

An unprecedented effort to catch up vaccination programmes that have fallen behind needs to take place now with the same energy and rigour as COVID vaccine roll out. Routine vaccine programmes need putting back on their feet and coverage rates need to stay high. And governments need to help educate people as well as invest – not cut investment - in this work now. If they do not, the end of 2021 could look like an equation no one wants to see. COVID + re-emergence of many other infectious diseases. It does not have to happen. We all must make sure it does not.