Public health officials are now thinking of how to protect people long-term as countries around the world pass the peaks of their first waves of coronavirus infections. It seems that the only way to do it is through gaining immunity if people can develop antibodies through vaccination or after getting infected and recover from the virus.

It needs enough people to become immune to develop "herd immunity" to protect the entire population. This will even protect those who are not immune because there are so many people that are immune that they prevent the virus to further spread in the community.

Herd immunity would effectively end the COVID-19 pandemic. But the vaccines will take at least 18 months to develop and so its massive distribution will have to wait for the meantime.

Earlier in the pandemic, some countries are planning to allow herd immunity to develop on its own by letting their people get infected. Although recovered patients will develop antibodies, a trail of deaths would also follow which is indeed a dangerous path to take.

Herd immunity, how does it work?

A certain portion of the population has to be immune to the virus to achieve herd immunity which depends on the number of people the average person with the virus can infect. This measurement is called Ro or read as "r-naught."

Ro is not a fixed number since it could decrease depending on the conditions. Specifically, if the people practice social distancing that they are too apart for the virus to spread or the number of the people who are immune increases so that the virus can no longer infect others.

The Ro needs to go below 1 to put the disease in decline until the virus dies out. Higher Ro means that a higher number of people are also needed to be immune to achieve the goal of herd immunity.

But the US is still far from 50% of its population becoming immune and it is hard to know exactly how far the country's immunity has come. Since there are still many people that are not tested because of limited testing, it makes it difficult to estimate the Ro.

Read: Coronavirus: Social Distancing May Prevail Until 2020 Unless Critical Care Capacity is Heightened and a Vaccine is Found, Says Harvard University

Dangers of pursuing pre-vaccine herd immunity

Some governments such as the United Kingdom have considered letting the virus spread through its population at the beginning of the pandemic. They have allowed public gatherings even after reaching 500 confirmed cases.

But they were prevented to continue their strategy as experts have advised that it could kill half a million people in the UK. They then advised residents to work from home and practice social distancing and the Prime Minister has ordered all UK schools to close down.

Similarly, it was also President Trump's plan to develop herd immunity by allowing the virus to spread but was advised by Dr. Anthony Fauci of the National Institute of Allergy and Infectious Disease that doing so could kill many people, reported by the Washington Post.

It is still far too early to think about intentional infection as many people now are getting sick through non-intentional spread that burdens the healthcare community.

Uncertainties on individual immunity

An early research done by Chinese scientists that have not been peer-reviewed said that some recovered COVID-19 patients did not develop coronavirus-neutralizing antibodies unlike those who did. Particularly, there are about 175 participants in the study that did not develop neutralizing proteins that are needed to confirm their immunity from the virus.

Their findings suggest that these patients are still at risk of reinfection. More so, even someone who has the antibodies might not be able to fight off an infection according to the report by Business Insider. Until now, it is still unclear how much antibodies can protect those recovered COVID-19 patients.

Furthermore, reinfection reports around the world are happening which escalates the uncertainty of being immune from the virus. Another reason why pushing for herd immunity without a vaccine is not a wise choice.

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