The Concept of Herd Immunity for COVID-19

The Concept of Herd Immunity for COVID-19

Corona Virus Disease 2019 (SARS-CoV-2) is an infectious disease, caused by newly discovered Corona Virus first reported in Wuhan, China in December 2019. WHO declared it as Public Health Emergency of International Concern on January 30, 2020, and a pandemic on March 11, 2020. Up until now, more than 5 million cases have been reported with more than 327K deaths in 216 territories across the world. Common symptoms of Covid-19 include fever, cough, shortness of breath, fatigue, chills, muscle pain, anosmia and ageusia. However, some people may acquire severe Acute Respiratory distress syndrome (ARDS) precipitated by cytokine storm, and multi-organ failure. The virus is spread by close contact between people, from droplets during coughing and sneezing. The time between exposure and onset of symptoms may range from two to fourteen days.

Recommended methods for prevention from this disease is frequent hand washing, face covering, social distancing, self-isolation in quarantine and keeping hands away from eyes and face. The standard test as devised by WHO for diagnosis of this disease is “real-time reverse transcriptase-polymerase chain reaction” from a nasopharyngeal swab. Chest Xray and CT may help in detecting the effects of the virus on the lungs.

According to the World Health Organization (WHO), there are no available vaccines or antiviral drugs against the coronavirus. Therefore, the treatment involves the management of symptoms and supportive measures, for example, Oxygen support and fluid Balance.

Researches for development of effective treatment started in January 2020 and several antiviral drugs are in clinical trials. While the vaccine preparation may take years, FDA has authorized medical healthcare systems to use convalescent plasma as an experimental treatment in cases where the person’s life is seriously endangered, with this unfortunate fact that there are no proven studies to show it as a safe and potential remedy for the disease.

With this, now comes the concept of Herd immunity, we have heard during this outbreak. Even leaders like Boris Johnson who survived Covid-19 was reported to preach herd immunity followed by a backlash by his own country’s scientific advisors.

Herd Immunity also called population immunity is:

“The proportion immune among individuals in a population” that should lead to a decline in the incidence of infection among individuals in a population. Herd immunity or herd protection develops when many people either are vaccinated against the disease or contract the disease and then become immune to it over some time because of their natural body immune system.

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To quote,

“Herd immunity is the status of all the people living in a local area and their ability to fight off a given infection,” says Jaquelin Dudley, associate director of the John Ring LaMontagne Center for Infectious Disease and professor at the University of Texas at Austin. “It has to do with the transmission ability of a given virus.”  

 In other words, Herd immunity is group protection that happens when a critical number of the population is immune to a certain disease. To achieve herd immunity, 70% or more of the population needs to get ill and build up antibodies to the new virus. Which help stop or slow the spread of an infectious disease. 

For antibodies, Natural immune system works and produces them by combating the disease after a person contract it. Therefore, if a person encounters the disease again, already formed antibodies safeguard the body and prevent the infection from occurring.

While many people are self-proclaiming herd immunity to be the need of the hour, we need to get an insight as to why herd immunity is not the solution to this ongoing pandemic. First of all, there is no Vaccine for Covid-19 yet. And as vaccines are the safest way to practice herd immunity, this leaves a big question mark on the thought of implementing herd immunity. On the other hand, Scientist does not know if there is a chance of recurrence of this disease, which again leaves the concept of herd immunity useless. Many individuals among the population are having a weak immune system, so they cannot fight virus making herd immunity risk to their lives. These individuals specifically include older people, infants, and immunocompromised patients. Also, for third world countries, it can cost the lives of their malnourished people with household status low-key. Furthermore, normal healthy persons can become very ill with exposure to COVID-19, and may develop serious side effects leading to death. Keeping all this in view, herd immunity can cause health care systems to become overburdened if many people get the virus at the same time.

 To quote some health professionals around the world, about their take on the implementation of herd immunity,

  1. “We don’t know yet if having the virus protects you from getting it again,” says Jared Baeten, a professor of medicine and global health at the University of Washington. The World Health Organization has emphasized 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,” Baeten says.
  2. Dr Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases and member of the White House Coronavirus Task Force, talked to TIME senior health correspondent Alice Park about herd immunity (among other things), and whether it was achievable with COVID-19 “We really can’t depend on herd immunity until we get either enough people infected, or enough people vaccinated, he said.”
  3. According to Gypsyamber D’Souza and David Dowdy, infectious disease experts at the Johns Hopkins Bloomberg School of Public Health. Herd immunity is still a long way away. But in the long run, as with any other infection, there are two ways to achieve herd immunity: A large proportion of the population either gets infected or gets a protective vaccine. Based on early estimates of this virus’s infectiousness, we will likely need at least 70% of the population to be immune to have herd protection. There are a few ways that might be achieved. In the worst case—for example, if we do not perform physical distancing or enact other measures to slow the spread of SARS-CoV-2—the virus can infect this many people in a matter of a few months. This would overwhelm our hospitals and lead to high death rates.  In the best case, we maintain current levels of infection—or even reduce these levels—until a vaccine becomes available. This will take a concerted effort on the part of the entire population, with some level of continued physical distancing for an extended period, likely a year or longer, before a highly effective vaccine can be developed, tested, mass-produced, and administered.

Thus, keeping all this in view, in future, if scientists succeed in making a vaccine against COVID-19, Herd immunity will be a better choice for the protection of a population.

To conclude this in the end, we can rightly say that the Herd immunity at present is not the answer to stop the spread of Covid-19. Once a vaccine is developed for this virus, establishing herd immunity is one way to help protect people in the community who are vulnerable or have low functioning immune systems. However, until then we will have to observe all the precautionary measures and guidelines given by WHO for protection against this deadly virus, which is causing massive destructive effects to populations around the world. This leaves us all with the message to practice STAY HOME, STAY SAFE!

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Aqsa Ashraf
Maryam Ashraf

Post by: Aqsa Ashraf & Maryam Ashraf

Aqsa is a third year MBBS student at KEMU, Lahore.
Maryam is a final year MBBS student at GMC, Gujranwala.
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