Building herd immunity against novel SARS CoV-2 is still away in near future

Herd immunity is only instituted when 60-90% population in a community becomes resistant to the infectious disease. To formulate the herd immunity, each infected person is able to transmit the infection to less than a person on average, that means once the rate drops below one, a community has achieved herd immunity. It won’t stop for each and every case, but it will certainly prevent the disease from spreading indefinitely.

Herd immunity against the infectious disease is acquired in two ways: developing and administering a safe and effective vaccine, or waiting for the disease to make its rounds through a population.

The best example of herd immunity is measles under special conditions, because it is highly contagious as more people need to immunized to reach it. One person in measles could infect 18 people in a susceptible population and 19 people out of 20 should get vaccinated to land herd immunity. Here everyone has to act as buffer between the infected person and new potential host to prevent the transmission of pathogen.

Research suggests that coronavirus has lower infection rate than measles, as it infects 2-3 people on average. It means the herd immunity should be achieved as more than 60- 70% of the population to become immune to COVID-19.

Vaccines can make a weapon repository for a disease without the body even having fights off the disease itself, that is why the herd immunity is something that’s achieved by vaccination rather than getting infected. Exposing whole population to the wild pathogen would be the highly dangerous way to cultivate herd immunity among survivors.

Can herd immunity stop COVID-19:

The ideas about herd immunity have been precipitating around as the potential solution to this devastating virus. This could develop via vaccination or exposing people to the infection is the way to eliminate the virus.

The main hurdle is that we are not even close to the wide spread resistance to COVID-19. Experts estimate that 60-90% population must have developed immunity to stop the spread. Most countries are affected by COVID-19 have not surpassed the 1%, indicating that it is still a long way from developing this.

Contracting the disease and to get recovered from is a risky procedure, however, vaccines are the vital options. Vaccines have already given evidence-based protection and are highly effective in reducing and eliminating the diseases with in the region e.g. measles, mumps and rubella. Smallpox (variola virus) has been completely eradicated with successful global eradication program. Vaccines have been successful in creating herd immunity to several infectious diseases.

Making vulnerable by not vaccinating could galvanize the outbreak that is under control in just keeping away.

Vaccines could have adverse effects in some cases or the immunity wanes away, depending upon the number of factors like severity and prevalence of the diseases, vaccines safety and individual patient factors etc.

One important thing to add in that the diseases are also prevented by adopting the social distancing norms, contact tracing, social isolation and quarantine, hygiene & sanitation, vector (intermediate host control) control, or cure of sick people before disease gets transmitted etc.

 Fig: COVID-19 mitigation strategies can help flattening the curve comparatively

https://www.nationalgeographic.com/science/2020/03/uk-backed-off-on-herd-immunity-to-beat-coronavirus-we-need-it/

People will continue to contract the diseases and die of infectious disease in the absence of established herd immunity. Certain proportion of population must be immunized to an infectious disease to control the spread. SARS CoV-2 is a contagious virus and communities are currently having no herd immunity either naturally or by vaccination.

SARS CoV-2 vaccines development trials (clinical and preclinical) are ongoing and it will take a year or two until the vaccine becomes available for public. But many factors are still remaining unknown at this time, to simply allow the virus to continue the turmoil without intervention:

-         Can people contract SARS CoV-2 more than once?

-         Positive antibody test doesn’t mean that person is immune from contracting the virus.

-         There is no cure, research is still ongoing.

-         Virus behaviour and its nature are bit complicated to understand.

-          Much of population is under risk for serious complications can lead to death. However, the young and healthy individuals also can develop complications moves to fatality.

-         It is not possible to get on the real number of patients, because of the healthy asymptomatic did not get tested.

The herd immunity phenomenon doesn’t work here by looking at the factors involving to make complications at various levels. As the small population is infected and it is highly risky to expose people to contract infection as they walk around freely taking no precautions and vaccines are not ready yet for public.

https://www.cnet.com/health/herd-immunity-what-it-is-and-how-it-can-slow-the-spread-of-coronavirus/

Any strategy in regards to achieve the herd immunity by exposing to the pathogen, a human challenge trial could be a quite controversial approach without the effective vaccine ready to use in public. This will likely to have deadly consequences and will contribute to rise in number of deaths.

At this point of time the scientists are not very clear whether human body even develops immunity after an infection with SARSCoV-2. If body becomes immune, there is no evidence that how long the immunity might last after recovery. Based on the studies done on MERS and SARS in the past, the scientists believe that person will have some immunity after recovering from the COVID-19, but there is yet much left to reveal. That is why, it is a dangerous and terrible idea to expose to the infection, which also have the potentials to spread the virus to those who might not be able to recover from it e.g. family and friends.

A number of people exposing themselves to the infections should not be taken as a process towards herd immunity. In fact, it is just putting people in a risk-benefit situation which is certainly not the smart choice.

https://time.com/5825386/herd-immunity-coronavirus-covid-19/

It is not feasible to regulate herd immunity until we get enough population to become immune in a community by vaccination, indirectly protecting the rest of the population that is not yet immune to the virus. To attain the herd immunity may occur in long term future, and the vaccination is a quite safer way to manage the same.

Building up herd immunity in near future is quite impossible until we have the effective vaccines ready for public. Adopting successful preventive measures are also securing time from us to develop a safe vaccine to immunize us, and hopefully, we will achieve the herd immunity that way.

Thank you!

Keep Safe and Stay Healthy