Blood tests conducted at the Schwabing Clinic on recovered patients demonstrated that the level of antibodies produced by the immune system dropped significantly in a majority of cases.
“In four of the nine patients, we saw sinking levels of neutralising antibodies,” said lead researcher Clemens Wendtner.
The study was conducted on the first confirmed German cases, who fell ill in January.
Mr Wendter added: “The extent to which [our findings] have an effect on long-term immunity and vaccination strategies is currently still speculative, but this will have to be watched carefully in the further course of the project.”
The findings align with research carried out in China, which concluded that the antibody response is not sufficient to create lasting immunity.
Doctors at the Chongqing Medical University found that the presence of the IgG antibody, one of the main antibodies induced through an infection, dropped on average of 70 per cent over a three-month period.
Not only do the results dampen hopes of long-term immunity in those who have been infected, but they also have implications for the development of a successful vaccine.
Trials carried out in the US by pharma giant Pfister gave hope this month that a vaccine is in the pipeline that can successfully prompt the body into developing antibodies against coronavirus.
Participants in the trial showed a higher level of antibodies than those developed by people previously infected with the illness.