The first studies carried out in the world to evaluate what part of the population has antibodies against the COVID-19 coronavirus have detected less immunity than expected, the World Health Organization (WHO) has warned. If this still preliminary result is confirmed in other studies that are currently underway, it would remove the prospect that the immunity of the population could increase rapidly and allow social distancing measures to be left behind.
Maria Van Kerkhove, technical director of the WHO Health Emergencies Program, indicates that a lower proportion of people with detected antibodies are seen than expected, indicating that a lower number of people were actually infected. In a study among blood donors in the Netherlands, for example, only 3% had antibodies against the coronavirus. Besides, according to WHO Director-General Tedros Adhanom, initial data from some of these studies suggest that a relatively small percentage of the population may have been infected even in heavily affected areas; no more than 2% to 3%.
However, the results are preliminary and a better understanding of how these studies have been done is needed to know if the population samples are representative and to what extent the results are conclusive.
One of the problems of seroprevalence studies is that rapid antibody detection tests are still not very sensitive ―some of them are only 40% sensitivity―.
An additional problem is that not all people who have been infected with the coronavirus develop antibodies equally. People with a severe clinical picture appear to develop a potent antibody response that is easily detected, while people with a mild clinical picture appear to have a lower antibody response, something that could indicate that people who have had mild forms of COVID-19 are less protected than people who have had more severe symptoms.
Editorial Disclaimer: information published during the 2020 COVID-19 pandemic may be updated frequently to reflect the dynamic nature of current understanding.