Covid-19 Other

Herd Immunity

What is it and why are we hearing so much about it during COVID-19?

Herd immunity  is a form of indirect protection from transmissible diseases or pandemics which occur when a large percentage of a population builds a resistance to an infection, either by vaccination or by previous infections, thereby providing a measure of protection for individuals who are not immune. In a population where a large proportion of individuals possess immunity, such people being unlikely to contribute to disease transmission, chains of infection are more likely to be disrupted, which either stops or slows the spread of disease. The larger the proportion of immune individuals in a community, the smaller the probability that non-immune individuals will come into contact with an infectious individual, helping to shield non-immune individuals from infection. link

Medical experts have hailed the advances in vaccines as being one of the major achievements in the 20th century, however, anti-vaxxers do not agree. Their increased opposition to vaccines have allowed preventable diseases to return to communities by refusing to allow their children be vaccinated or to be vaccinated themselves. It has also been seen in poorer countries to encourage herd-immunity to save money on vaccination. Some anti-vaxxers cite their religion as a reason to not vaccinate. Others believe that diseases have disappeared due to better sanitation and hygiene, not vaccines. This has been proven false by the comeback of previously eradicated infectious diseases. link

What does the World Health Orgaisaition have to say about it?

Dr Michael Ryan who is Executive Director, WHO Health Emergencies Programme told a press briefing in Geneva in mid May;

“Humans are not herds,” He went on to say: “I think we need to be really careful when we use terms in this way around natural infection in humans because it can lead to a very brutal arithmetic which does not put people and life and suffering at the centre of that equation.”

He said “no one is safe until everyone is safe”, adding: “So I do think this idea that ‘maybe countries who had lax measures and haven’t done anything will all of a sudden magically reach some herd immunity, and so what if we lose a few old people along the way?’ – this is a really dangerous, dangerous calculation.

People with Covid-19 can be categorised into three groups;

  • those with no symptoms
  • those who get a mild form of the disease
  • and those who become very ill with Covid-19.

According to Dr Fidelma Fitzpatrick, Consultant Microbiologist at Beaumont Hospital 

“We don’t know yet if those asymptomatic patients [now considered to be a much larger group than first thought] who carry and spread the disease have immunity to Covid-19 or not,” explains Fitzpatrick.

UK and herd immunity

In May 2020, Mr. Patrick Vallance, the British Government’s Chief Scientific Adviser has apologised for not being clear when he previously presented the concept of “herd immunity”, in March as a potential way out of the coronavirus pandemic, saying he didn’t mean that was the government’s plan. link. “I should be clear about what I was trying to say, and if I didn’t say this clearly enough then I apologise,” he said. “What I was trying to say was that, in the absence of a therapeutic, the way in which you can stop a community becoming susceptible to this is through immunity and immunity can be obtained by vaccination, or it can be obtained by people who have the infection.” UK currently have 36,393 deaths.

Sweden and herd immunity

Sweden only imposed very light restrictions on daily life. Schools, bars, restaurants remain open.Their Public Health Authority have confirmed that only about 7.3% of the residents of Stockholm have developed antibodies to fight off COVID-19, which falls way below the 70%-90% required to create ‘herd immunity’. Sweden currently have 3925 deaths. This is substantially higher than that of its neighbours, Denmark 561 deaths, and Finland 306 deaths .

USA and herd immunity

A new study cited by New York Governor Andrew Cuomo, on 3,000 people across the state, 13.9% exhibited COVID-19 antibodies (21% in New York City), implying that 2.7 million people across the state had been exposed to COVID-19, according to Bloomberg, ten times higher than the presumed infection rate. link The World Health Organization has emphasised that we do not know if people who recover from COVID-19 are capable of getting sick again with the virus. “Individual immunity is not yet proven, much less herd immunity,” Jared Baeten, a professor of medicine and global health at the University of Washington has said. Baeten also states “When a vaccine does become available, we will only be able to achieve herd immunity if the vast majority of people get vaccinated”. Jaquelin Dudley, Associate Director of the John Ring LaMontagne Center for Infectious Disease and professor at the University of Texas at Austin agrees saying “The vaccine is our best hope to improve herd immunity [and boost] the number of people that can resist the infection when they’re exposed,”. The USA have had 95,213.00 COVID-19 deaths.

Spain and herd immunity

Spain has been one of the countries worst-hit by COVID-19 with over 28,628 deaths. Mr. Salvador Illa, Spain’s health minister said “there is no herd immunity”.