Herd immunity, where art thou? ‘Vaccines first’, say experts

People wearing masks Herd immunity (Image: Shutterstock)

During the first months of the pandemic, the idea of herd immunity enamoured us. Can’t blame us though. Back then, the prospects of a COVID-19 vaccine looked bleak.

To our simple minds, it seemed like a magical solution to a complex problem. What if we voluntarily infect ourselves and miraculously gain immunity from the virus? Wouldn’t that be nice?

But are we anywhere closer to attaining herd immunity? It’s been months since the virus first threw a wrench into our sad lives.

That’s probably because we have interpreted herd immunity in very asinine terms. Ok, maybe I only speak for myself.

Forget the plebs, even political leaders like UK’s Boris Johnson and US’ Rush Limbaugh were guilty of oversimplifying how it works.

Johnson even claimed back in March that the UK will experiment with herd immunity instead of taking the standard route like testing and contact tracing.

In the US, people even toyed with the idea of “controlled voluntary infection.” In short, have a “coronavirus party” where people can meet, mingle, swap viruses and, voila! herd immunity!

But simply standing in the way of an infected person’s sneeze will not make us immune to the coronavirus.

“Someone who goes to a ‘coronavirus party’ to get infected would not only be substantially increasing their own chance of dying in the next month, they would also be putting their families and friends at risk,” warned Johns Hopkins in its official communication.

What is herd immunity?

When most people become immune to an infectious disease, it provides indirect protection to those who are not immune to it. ‘Do NOT wear N95’: CDC just schooled us on how to wear a mask

The pathogens — in this case the virus — can’t jump from person to person if most people are already immune to them. It significantly reduces the size of the virus’ playground. Sad for the virus but good for us!

Diagram explaining herd immunity
How herd immunity works (Image: Wikimedia Commons)

But to reach there for COVID-19, 70% or more of the population would need to be immune, says Johns Hopkins Coronavirus Research Center. How much sugar can you have safely?

But this immunity doesn’t come from exposure to the virus but from immunisation. Experts also say that we should think of herd immunity only in terms of vaccines.

In one of World Health Organization’s educational videos, Chief Scientist Dr Sowmya Swaminathan explains it in simple terms: “Let’s take an example of a disease like measles, which is a very common childhood infectious illness, caused by measles virus, for which there is a very effective vaccine. Now we say that to achieve it, we need about 95% of the people to have immunity or antibodies.”

diagram explaining herd immunity
Herd immunity (Image: Wikimedia Commons)

Even if 5% of kids are not vaccinated, the others who are immunised prevent the virus from spreading to the others. What is ‘Long COVID’ and who is at risk?

“So, it’s really like having a barrier of people who are protected, who break that chain of transmission. So you don’t need every single person in the area, in the population, to necessarily be protected,” Swaminathan says.

What about coronavirus parties and swapping viruses?

“The SARS-CoV2 virus is a highly transmissible virus. We think it needs at least 60% to 70% of the population to have immunity to really break the chain of transmission,” says Swaminathan. Social distancing in vampire bats & other lessons in how animals stay healthy

While herd immunity may happen eventually, it will take a lot of time. More importantly, Swaminathan believes, it will cause a lot of collateral damage.

Even 1% of the infected people will ultimately die. “It can add up to a huge number of people if we look at the global population,” she explains.

According to a study titled “The Signature Features of Influenza Pandemics — Implications for Policy,” herd immunity for a flu pandemic like COVID-19 may take two to three epidemic waves.

“… each interrupted by the typical seasonality of influenza virus and more rarely by interventions, with the help of cross-protection through immunity to previously encountered influenza viruses, and vaccines when available.”

COVID-19 has a fatality rate of 0.% to 1.3%. Without good patient management systems, it’s a fatal mistake to achieve it by letting the virus run amok, says the same study.

By assuming a positive threshold of 50% for countries like the USA and France, at least 100k to 500k people will die.

People, especially men, with underlying diseases like diabetes, cardiac arrest, respiratory disorders or obesity will be particularly at risk.

“It’s not a good idea to try to achieve herd immunity by just letting the infection run wild. We should talk about it in the context of a vaccine,” reiterates the Chief Scientist.

The strategy is to vaccinate enough people than just letting the virus “safely” infect them. “Because with the vaccine you can achieve immunity and herd immunity safely,” she says.

Some hope?

By August 2020, six COVID vaccines have reached phase III trials. So we can expect some will be available by early 2021.

Vaccines will work better because they will protect the highly-exposed population first like frontline workers. They will reduce the spread of the virus by preventing its transmission at the most vulnerable spots.

So till we get vaccines, no coronavirus parties or herd immunity for any of us. Wash your hands, wear a mask and follow socially conscious behaviour till then.