As we know that coronavirus has infected large numbers of people but yet it is not clear exactly how many people have been infected so far.
The whole world has been caught with coronavirus since December 2019 and the virus leads to an illness known as COVID-19. Infections are increasing day by day. As it is a new disease still infections are trickling. There is a lot of uncertainty about the pandemic and how many people are infected so far is not clear.
Serosurveys have been conducted in several cities across the country since the last two months including Delhi, Bangalore, Mumbai and Pune. And these results suggest that COVID-19 is far more widespread than virus tests show. In Assam, the first serosurvey launched in Guwahati. The survey is being conducted by an NGO, Srijanasom, in association with the Medicity Guwahati Group of Clinic and Diagnostics.
What is serosurvey and what does it indicate?
It is also known as a serological survey which is for collecting blood samples to determine whether a person is infected with the COVID-19 pandemic and to detect whether the person was infected with the coronavirus in the past. Further, it also identifies antibodies that are being produced to combat COVID-19.
Or we can say that serosurvey involves the testing of blood serum of a group of individuals. This will be used to monitor the trends in the prevalence of coronavirus infection at the district level.
The test can show that a person is exposed to the virus but as per some authorities, such tests have limits to what they can tell us. The test looks at blood serum which is the fluid part of plasma that is left after cells have coagulated. It also tells about the presence of antibodies as discussed above which are responsible for specific virus antigens. But scientists have yet to confirm how effective is novel coronavirus antibodies or immunoglobulins are in protecting from a second infection.
Key findings of the test are as follows:
– More than 51% in Pune were tested who showed the presence of antibodies specific to the coronavirus. It suggests that about half the population of this city of 4 million could have already been infected.
– Earlier exercise in Delhi had suggested that the particular spread might be 40 times the number of confirmed cases.
– According to the second survey in Delhi, around 29% has antibodies for COVID-19.
– About 40% of the sampled group in Mumbai was found to be infected and Berhampur in Odisha showed 31%.
These numbers are averages with various variation between neighbourhoods. Cases varying in Mumbai for example from 16% to 57%.
What we come to know thorough these findings?
These numbers confirm the general impression that most COVID-19 infections are asymptomatic. Whereas according to some estimates approximately 80% are asymptomatic. It is also said that mainly within families, the virus could be spreading from asymptomatically infected people also.
In March, at the start of the outbreak from a capacity to test a few hundred to more than 8 lakhs test a day now which means that there has been a massive upgrade in the testing infrastructure. And as per the serological test, vast majority of the infected people are still being missed out mainly those who rae not showing symptoms.
Serosurveys are leading to herd immunity, Yes or No?
These surveys are not designed to detect neutralising or protective antibodies in human beings. As all antibodies are not protective. Only neutralising antibodies can make a person immune to the disease. Also, scientists are not aware of the level of infection in the population at which ‘herd immunity’ would start to play a role.
What is herd immunity?
It is also known as community immunity. It is when a large part of the population of an area is immune to a specific disease. Herd immunity protects at-risk populations. These include babies and people whose immune systems are weak and can’t get resistance on their own.
As per the current scenario adequate testing is important to containment strategies. This is the only method to identify and isolate, infected people and their close contacts. It is clear that if the tests are done will be more then there will be a greater chance of detecting infected people, including those who are asymptomatic. Also, timely isolation can prevent transmission to other people. The higher number of tests can help in slowing down the spread of the disease.