Scientists from Robert Koch Institute report a significant decrease in case notifications for almost all notifiable diseases during the first months of COVID-19 pandemic and its associated non-pharmaceutical interventions in 2020 in Germany. These findings are based on a thorough analysis of different surveillance data: surveillance of nationally notifiable infectious diseases as well as the national virological sentinel surveillance system. Both studies have been published in The Lancet Regional Health – Europe:
One study, based on national disease notification data, is the first to examine the impact of the COVID-19 pandemic and associated non-pharmaceutical interventions on the full spectrum of infectious diseases under national surveillance. COVID-19 dominated infectious disease surveillance: more than half of the total reported cases were COVID-19. In parallel, a large decrease of -35% in case numbers for nearly all infectious diseases was recorded, especially among younger and older age groups. Case numbers were compared to previous years, taking seasonality and trends over time into account. The largest decrease was observed for cases of infections transmitted via the respiratory route, especially for measles (-86%), whooping cough (-64%), Haemophilus influenzae infection (-61%), seasonal influenza (-54%) and chickenpox (-52%), and imported vector-borne diseases dengue fever (-75%), and malaria (-73%). By contrast, cases of tick-borne encephalitis (endemic in some parts of Germany), increased by +58% compared to the expected case number. Gastro-intestinal infections also decreased to a large extent, especially cases of rotavirus disease (-83%), shigellosis (-83%), and norovirus disease (-79%). Less affected were bacterial healthcare associated pathogens, such as MRSA (-28%), reduced by about one third, and cases of sexually transmitted and blood-borne diseases (-28% for hepatitis B, -28% for hepatitis C, -22% for HIV, and -12% for syphilis).
The other study, based on the national virological surveillance system, complements these findings with comprehensive laboratory analyses: The nationwide network of sentinel physicians contributing to the “Working group on influenza” (Arbeitsgemeinschaft Influenza) performing a surveillance of acute respiratory infections, sent over 3,000 patient samples to the National Influenza Center at the Robert Koch-Institute. Lab testing for multiple respiratory viruses revealed an unprecedented decline of seasonal influenza (A/B), respiratory syncytial virus (RSV A/B), metapneumovirus, parainfluenza virus (types 1-4) and rhinovirus. This decline was sustained over months, with a single exception: Rhinovirus resurged to levels equaling and even exceeding those of previous years. This rebound could be due to lower levels of population immunity to this virus, its better environmental resistance and its high prevalence in young children.
The reason for this changing dynamic is multifactorial, including a change in healthcare utilization, and reduced transmission due to the non-pharmaceutical interventions and reduction in mobility. These findings are reassuring in terms of effectivity of the measures to prevent infectious disease transmission, which reduces the burden of disease in the population, as well as the burden on the healthcare system.