Parvovirus B19 nucleic acid detection rates in German blood donors before, during and after the restrictions of the SARS-Cov2 pandemic (2015-2024)

In healthy adults, parvovirus B19 (PVB19) usually causes mild symptoms like fever and itching when infecting red blood cells. But in immunosuppressed or those with high red blood cell turnover, severe complications like chronic pure red cell aplasia or transient aplastic crisis can arise. Besides respiratory transmission, infection through blood products is possible, leading to virus testing of blood products in Germany.

Between January 2015 and April 2024, we screened 2,105,755 blood donations for PVB19. DNA was extracted from pools of 96 samples and specific detection of nucleic acid was carried out using a polymerase chain reaction. Incidences were determined for three different periods: January 2015 - March 2020 (pre-COVID-19), April 2020 - March 2023 (during COVID-19 pandemic; end of the mask requirement in the public sector in Germany in April 2023) and April 2023 - March 2024 (post-COVID-19).

In the periods defined above, a total of 242 PVB19 positive donations were identified. For the first period under consideration (2015 - 2020), 101 PVB19 positives were found in a total of 1,228,361 donations, resulting in an incidence of 0.83 per 10,000 donations. In the second period (2020 - 2023), PVB19 was detected in 4 of 621,222 donations, resulting in an incidence of 0.06 per 10,000 donations in this period. Within the third period (2023 - 2024), PVB19 was detected in 137 of 235,088 donations, resulting in an incidence of 5.35 per 10,000 donations with a striking increase in incidence between December 2023 and March 2024 (4.3 to 21.1/10,000 donations), challenging the testing regime of blood donation services.

Most of the population is immune to PVB19, as immunity from a single infection usually lasts a lifetime. This is accompanied by a stable incidence, as we observed between 2015 and 2020. In our study, the interventions taken because of the SARS-Cov2 pandemic, such as mandatory masks and social distancing rules, also led to a drastic decline in the number of PVB19 infections as PVB19 is transmitted mainly via the respiratory route. A relapse to higher incidence than pre-COVID19 was recorded after the measures ended. In summary, the data from our routine blood donation testing provides interesting insights into the epidemiology of PVB19 and underline that the hygiene interventions during the COVID19 pandemic had a lasting impact on PVB19 infection rates.

Funding statement: T.V. was supported by the German Federal Ministry of Education and Research (BMBF, project HepEDiaSeq — FKZ 01EK2106A).