The COVID 19 pandemic continues to spread, with millions of cases and thousands of deaths. To slow the spread and reduce mortality, governments around the world have introduced measures of social distancing. When these measures are lifted, the "epidemic curveIs expected to decrease in the absence of a vaccine.
As more and more tests are performed in hospitals in the United Kingdom and many other countries, the confirmed cases to date are largely recorded in people with symptoms. But to accurately predict the consequences of lifting restrictions, we need to understand how many people with COVID-19 asymptomatic and to what extent the virus is contagious.
The findings are in line with a survey conducted in an Italian village that was at the center of the infection and showed that 50% -75% were asymptomatic, but represented "a terrible source" of infection. A recent study from Iceland also showed that about 50% of people who tested positive for COVID 19 were asymptomatic.
In the meantime, a study WHO found that "80% of infections are mild or asymptomatic, 15% are serious infections and 5% are critical".
Although we do not know which 80% were purely asymptomatic or exactly how these cases were calculated, this again shows that a large majority do not go to the hospital at all for any examination.
The new BMJ study is seemingly different from the findings of previous studies, suggesting that the completely asymptomatic ratio of COVID 19 is small: 17,9% on the cruise ship Diamond Princess and 33,3% of Japanese who left Wuhan.
The new publication is based on aggregate data that the Chinese authorities have been publishing daily since April 1 on the number of new coronavirus cases in the country that are asymptomatic.
He states that "a total of 130 of the 166 new infections (78%) detected in the 24 hours until the afternoon of Wednesday, April 1 were asymptomatic." He also said that the 36 accidental cases "involved arrivals from abroad", according to the National Health Commission of China.
The new BMJ data is extremely important as the majority of new information and findings circulating daily around the world come from a potentially small percentage of people who have shown symptoms, sought hospital help, tested positive and found positive. . The difference from previous epidemics such as SARS is that there were symptoms and they could be detected.
Finally, extensive antibody testing, which are not yet realized, will be able to tell us how many people already had COVID 19. This will give us a better approach to the total number of infections which is very important in making decisions to lift restrictive measures.
For example, if antibody tests show that a large percentage of the population already had COVID 19, asymptomatic and undiagnosed people are less likely to spread the infection as soon as the restrictions are lifted. However, if only a very small portion of the population was infected, then lifting the measures may need to be delayed until vaccination strategies are completed.
The article was published in The Conversation from Jasmina Panovska-Griffiths, Senior Research Fellow and Lecturer in Mathematical Modeling, UCL with Creative Commons license. Read it original article.