Delhi Government to start Sero-surveillance every month to combat COVID. Here is what it means

After a period of staggering rise in infections in the past month, experts feel Delhi is on the road to recovery. From increased beds, measures and a testing rate which is greater than the national average, Delhi has been praised as a COVID-19 model as well. The government has also started more rampant testing in containment zones. A recent survey found that as of July, at least 15% of Delhi's population had been exposed to the virus. While officials say that there is a long way before the city flattens the curve, one of the newest measures the government has taken is the plan to start sero surveillance mapping every month, going forward.

The announcement was made by Delhi's health minister, Satyender Jain, who himself returned to office after suffering from COVID-19. It has been said that the sampling would be done from the 1st to 5th of every month.

Currently, the number of COVID-19 cases in Delhi amount to 1,23, 747 cases with more than 1,04,000 recoveries, which is one of the highest in the country.

While a vaccine or a definite treatment plan is not available to us, experts believe that the only way to prevent further spikes in infections or find out the actual data about exposure levels is to test the presence of antibodies in people.

Sero surveillance is a globally used and trusted standard which measures the levels of antibodies against a certain infection and decodes the percentage of the population which has been previously exposed to the virus. A recent survey from Delhi showed that at least 15-20% of the population had already been exposed, or are immune to the deadly SARS-COV-2 virus.

The tool is also used as a measure for officials to check on mass inoculation and see the level of immunity people have. Even before COVID-19, it was used as an extensive tool to see how far an infection has breached in a community. National serosurveillance programs are well established in many countries worldwide.

Data released by nationwide sero-surveillance done by Indian Council of Medical Research (ICMR) revealed that by June, only 0.73% of the sample population was infected by the deadly COVID-19. The virus has infected 1.19 million people in the country so far, making it the third-worst country affected by the pandemic.

Serosurveys, conducted over time could also inform officials about statistical data regarding any disease. For example, with an infection as scary and rapidly spreading as COVID-19, a serosurvey could provide information about what percentage of the population in a given city or district may have acquired some sort of immunity to the virus. It could also give them inputs about what further measures to take, where is the disease more concentrated or the age groups which might be more at risk.

Hence, serosurveys done over a period of time, or conducted every month, just like what has been detailed, can be one of the ways to measure the spread of the disease or map consequent spikes of the infection.

Sero surveys derive results from the presence of antibodies, proteins meant to fight off infections which are part of the body's immunology make-up. For a serosurvey, sample blood tests are done and if the antibody levels in the blood are detected, it can mean that a person has considerable immunity against the said infection. Sero surveys done routinely could also show how long do antibodies last in the body and provide immunity against the disease, which is a pressing concern.

Another benefit of serosurveillance is to observe if a vaccine can actually provide immunity. Given that we have a vaccine ready for the masses by the end of 2020 or early 2021 (which may or may not be possible), a serosurvey could show if the COVID-19 vaccine being deployed to the masses is actually working. Sero surveys could also identify any infection cases (asymptomatic, mild ones, or ones which may have gone away on its own) which may have been missed.

Apart from this, serosurveillance has also been depended upon to identify trends of a certain disease, the burden of infection, predict potential outbreaks, new or emerging pathogens and in a way, help contribute to the rooting out of rampant infection.

In the past, sero surveillance has been used to map the spread of diseases and infections like Hepatitis B, hepatitis C, diphtheria, tetanus, polio and mumps.