New coronavirus vaccines are seen as crucial for the protracted launch of the Tokyo Olympics and Paralympics less than a year away. But a number of research studies are showing people infected with COVID-19 have lost their immunity to the infection within a few months, casting a shadow over Japan’s hopes to give a much-needed shot in the arm to its battered economy.

The research has poured cold water on the optimism of vaccine manufacturers who have been working around the clock to produce mass vaccinations that boost antibodies in people against the disease.

Still, experts say that it may not be as bad as it seems. A King’s College London study of more than 90 people infected with COVID-19 showed that the levels of antibodies peaked three weeks after the onset of symptoms, and then declined rapidly. Only about 16.7 percent of them had elevated levels of antibodies three months later. Similar findings have been reported in Spain as well.