Amsterdam institute for Immunology and Infectious diseases

Corona led to many socially disruptive measures. However, these had a positive side effect: other infectious diseases decreased enormously. This suspicion has now been demonstrated for the first time with solid figures in an article published this week in The Lancet Digital Health.

Since the introduction of lockdown measures, the number of cases of serious bacterial infections has decreased drastically worldwide. For this study, the Dutch Reference Laboratory for Bacterial Meningitis, housed in Amsterdam UMC, provided the figures for the Netherlands.

"You see a spectacular drop in the number of infections studied. In all participating countries," says Nina van Sorge, head of the reference laboratory. "I will probably never experience this again."

The researchers, led by Angela Brueggemann of Oxford University in Great Britain, looked at three infectious bacteria that are mainly transmitted via the respiratory tract: Streptococcus pneumoniae, Haemophilus influenzae and Neisseria meningitidis. As the words suggest, these are the main causes of serious infections such as pneumonia, blood poisoning (sepsis) and meningitis.

26 countries Laboratories from no fewer than 26 countries around the world provided data on the number of infections recorded for each of the bacterial species. This article covers the first period, say the first coronal wave of spring 2020. Publications on the later periods are in preparation.

The researchers added up the number of infections per bacterial species and see a clear link between the measures taken in mid-March 2020, such as the one-and-a-half metre distance, mouth masks, hand washing and reduced mobility due to working from home and shop closures, and a decrease in the number of serious bacterial infections caused by the three pathogens.

The number of infections with Streptococcus pneumoniae fell by 68 per cent four weeks after the start of covid and after eight weeks fell further by 82 per cent compared to the previous years. In the Netherlands, too, the decrease was of this order of magnitude. "We see this in all countries where measures have been taken," says Van Sorge. "It is difficult to precisely map the effect of certain measures, but we see that reduced mobility through working from home has the greatest effect. Differences between countries with and without compulsory mouthguards or school closures are less clear."

To be sure that the results are really due to a decrease in the number of infections and not due to careless registration because of reduced sending in, the data on a bacterium that is transferred from mother to child shortly after birth are also included. Because this fourth bacterium is passed on shortly after birth, the anti-coronas measures could not have influenced it, was the thought. Indeed, it turned out that the number of reported cases of this bacterial infection did not differ from the period before corona.