The watchword for blood donation: safety

In 2020, another virus was added to the list of those that Swiss Transfusion SRC keeps under constant surveillance: the new strain of coronavirus.

Swiss Transfusion SRC strives to ensure a high standard of safety for donors and patients. Among other things, this entails the regular monitoring of the effects of viral and other pathogens that could potentially be transmissible by blood.

Coronavirus: risk assessment ongoing

Despite the Covid-19 pandemic, people were able to donate blood in Switzerland throughout the year, subject to numerous safety precautions introduced to protect both patients and donors. Wait periods were imposed for blood donors who had been infected with the coronavirus. Swiss Transfusion SRC provided informational materials to the regional blood transfusion services for use by their staff and donors.

To assess the risks that the coronavirus poses for blood donation/transfusion, Swiss Transfusion SRC drew on recommendations issued by Swiss and European authorities and intensified its own exchange with experts from its European partner organisations. Working with the regional blood transfusion services, it issued regulations that applied nationwide; which it then regularly assessed and adjusted as necessary. There is still no evidence for the transmission of the coronavirus through transfusion of blood.

Convalescent plasma in the spotlight

The use of convalescent plasma to treat virus outbreaks predates the Covid-19 pandemic, but in those cases, it had been used in connection with outbreaks specific to particular regions, such as those of Ebola and SARS. The use of convalescent plasma to treat the coronavirus marks the first time this therapy comes into use on a global scale. In this case, the plasma is collected from individuals who have recovered from a Covid-19 infection and have developed an immunity to the virus. Their plasma contains antibodies that are able to specifically target this particular pathogen.

Not long after the pandemic started, convalescent plasma became available in Switzerland for use in clinical studies or as an experimental therapy for individuals. Swiss Transfusion SRC, working with groups made up of its own experts and those of the regional blood transfusion services, drew up a set of criteria for donated convalescent plasma, laying down requirements for both donor selection and the production process. The aim was to ensure the safety of both the donors and the blood products.

Clinical studies conducted in numerous countries throughout the world have been evaluating the efficacy and safety of convalescent plasma in the treatment of Covid-19 infections since the start of the pandemic. Swiss Transfusion SRC is one of the partners working within the “Support E” project at the European level. Within Switzerland itself, two studies acquired the planned number of study participants in 2020; other studies will follow. The data available thus far indicate that convalescent plasma is most effective when administered at an early stage of the infection, i.e., before a patient becomes critically ill.

Highly sensitive tests for donated blood

No HIV-positive samples were detected in 2020 in testing performed on every unit of blood donated (2019: 1). Somewhere between one and six infected units were found in each of the ten years before that. A total of 9 donations infected with hepatitis C were detected and destroyed, a value on a par with past years. Testing for hepatitis B resulted in the detection and destruction of a total of 34 infected donations in 2020 (2019: 30).

Hepatitis E (HEV) has been subject to mandatory reporting since 2018. The Federal Office of Public Health (FOPH) reported a decline in the number of HEV cases in 2020. Of the total of 71 cases reported in Switzerland (2019: 113), 43 were detected in blood donations.

HEV is transmitted from animals to human beings via the food chain in Europe. The decrease in the number of cases probably reflects a change in the level of exposure of the population and/or in the number of animals infected (primarily pigs). Changing consumption habits may also play a role. An analysis to be conducted by Swiss Transfusion SRC in 2021 should reveal which of these factors are involved in the changes in HEV case numbers. By then, Swiss Transfusion SRC’s experts will have two years’ worth of data to work with.

Hepatitis C positive blood units detected in time
First-time donorsRegular donors

Hepatitis B positive blood units detected in time
First-time donorsRegular donors

HIV-positive blood units detected in time
First-time donorsRegular donors

HEV-positive blood units detected in time
First-time donorsRegular donors

Tropical pathogens in Northern Europe

Swiss Transfusion SRC monitors the incidence and distribution of blood-borne diseases. When necessary, it defines risk areas and takes steps to keep the blood donors and patients safe. For instance, individuals who have travelled to a risk area have to wait for a certain period before they can donate blood. The wait period is normally one month.

In 2020, numerous cases of the West Nile virus were once again reported in Europe. This virus is transmitted by the tiger mosquito. The 2020 data are comparable to those from 2019. The first cases were detected in the Netherlands; previously unaffected regions in Germany and Spain reported their first cases. Most of the cases were in Eastern Europe or Northern Italy, as has been true for the past ten years. There is no evidence for a locally acquired infection with the West Nile virus in either human beings or animals in Switzerland. Should it become necessary, all donated blood could be tested for the West Nile virus within a very short period.

Several autochthonous cases of dengue were reported in limited regions of France in 2020, and Italy reported its first autochthonous case. No infections with the Zika virus were detected anywhere in Europe in 2020. Europe’s last reported case of the chikungunya virus was in Italy in 2017.