Vaccines have been used to protect people from diseases since the 1800s. They are one of the most effective public health tools we have. Vaccines work by introducing a small number of weakened viruses into your body so that your immune system can learn how to fight them off before they ever get a chance to cause you any harm. That’s why it is important for everyone around you, especially those who are too young or too sick, to be vaccinated to work effectively for herd immunity.
In this blog post, we will discuss: 1) herd immunity; 2) How herd immunity is achieved ; 3) How close we are to herd immunity for Covid-19.
What is herd immunity?
Herd immunity is when a large portion of the population has become immune to a disease, making the spread of that disease from person to person unlikely. As a result, those who have not contracted it also gain this protection.
A percentage of the population must be capable of contracting a disease for it to spread. This is called a threshold proportion. If the proportion of immune people in a population is higher than this threshold, we’ll have herd immunity, and the spread of the disease will decline.
How is herd immunity achieved?
There are two main ways to achieve herd immunity for COVID-19: infection by virus and vaccination.
Natural infection
Herd immunity has the potential to occur when a significant portion of people have recovered from a disease and had protective antibodies against future infection.
This can create problems with relying on natural infection to create herd immunity from Covid-19 virus ;
Reinfection. After recovering from COVID-19, it’s not clear how long you are protected before getting sick again. Even if you have antibodies to the virus, it’s possible that you could get COVID-19 again.
Health impact. Experts estimate that more than 45 million people would have to recover from COVID-19 before a pandemic can be halted in the UK. If these many infections are sustained, they could lead to serious side effects and millions of deaths among older adults and those with health conditions. If this happened, the healthcare system would quickly become overwhelmed.
Vaccines
Herd immunity is achieved when enough people are vaccinated against a specific disease and the antibodies develop resistance to future infection. Unlike a natural infection, vaccination does not cause illness or complications; in this way it maintains public health by preventing widespread contagion. Using the concept of herd immunity, vaccines have successfully controlled contagious diseases such as measles, polio, diphtheria, and many others.
Measles provides a good example of how herd immunity works. It is a highly contagious infectious disease, and we have very effective vaccines for it. Public health experts say over 95% of the population is immune to measles with the available vaccine. Herd immunity proves to be a barrier against the disease, with immune people breaking the transmission of potential diseases to the vulnerable population.
How close are we to herd immunity for Covid-19?
Experts say that to break the chain of infection, a minimum of 80% of the population should be immune through either prior infection or immunization. However, reaching herd immunity through vaccination against COVID-19 might be difficult because of many reasons.
Vaccine’s effectiveness – The COVID-19 vaccines, developed by Moderna and Pfizer, have an extremely high success rate in preventing symptomatic disease. Nevertheless, it is unclear whether the vaccine protects against infection or transmission to others.
New variants – New Variants of SARS-CoV-2 are emerging that might be more transmissible and resistant to vaccines. “We’re in a race with new variants.” The longer it takes to stop the spread of the virus, the more time these variants have to emerge and spread.
Vaccine roll-out is inconsistently distributed –The COVID-19 vaccine distribution has varied among countries and within communities. If one community achieves a high vaccination rate, outbreaks can occur if a high volume of population mixes with surrounding areas that lack the same level of immunity.
Vaccine production and distribution are rapidly scaling up. In the United Kingdom, more than 38 million people have already received a dose of a coronavirus vaccine which will eventually reach that nation’s goal for herd immunity in just a few months. As winter nears, hopefully, enough of the population will be vaccinated to prevent another large surge. For this positive scenario to happen, widespread vaccine uptake is required among all parts of the population—including all ages and races, in all cities, suburbs, and countrysides.
Vaccines cannot prevent transmission of the virus, but they can protect you from severe disease and death. The vaccine is an astonishing development, but it’s unlikely to halt the spread of the virus completely, so we need to think about how we can live with COVID-19. Even without herd immunity for each other, vaccinating vulnerable people seems to be reducing hospitalizations and deaths from COVID-19. Though—likely years—before all waves of spread end, its prominence to society is likely to fade.
