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Herd Immunity and Covid-19

Herd Immunity  and  Covid-19

Introduction :
Now-a-days  it is our regular fight against  the danger of infection by the most contagious  disease  Covid-19 ; We fight it at  all levels,  at personal level, by maintaining social distancing  & proper sanitization,  at  local level  & also at  national level  by observing  various measures  instructed by the Authorities ;  In this context  we sometimes hear the term  ‘Herd Immunity’ ;  Recently the British Prime Minister Mr. Boris  Johnson also mentioned this term as a good measure of fighting against  Covid-19 ; What is this ‘Herd Immunity’ ?  How can it be achieved ?  How far it is suitable to  fight  against Covid-19 ?  To the non-medical general people like us  it will be convenient if we discuss it  briefly in  very simple terms ;

What is Herd  Immunity ?
‘Herd Immunity’ is the term used for social or group immunity ;  That is, it is the immunity at social level ;  When most of the persons in a given group or society gets immune or resistant to a particular virus which is contagious &  normally spreads  from person to person, the group or society can be said to have obtained  herd immunity against that virus ; In that case if one person gets infected,  it is much less likely that he will  be able to unknowingly spread it easily to another person ; In this way, the elderly persons, pregnant women, children or persons suffering  from other diseases of that society, who are less  or not at all immune to that virus,  are saved ;  The Critical Percentage  or  the ‘Threshold Limit’ of population which must be immune to stop spreading a virus is different for different diseases ; As for example for the disease of Measles, this threshold limit is 95%,  that is,  about 95% of a population have got to be immune to achieve herd immunity against that virus ;  However, for ‘SARS-CoV-2’  or  Novel Corona Virus experts predict at least 70 % of the population need to be immune to the virus in order to achieve herd immunity ;
 The Various Ways  of  Achieving  Herd  Immunity :
Herd Immunity or group immunity can be achieved in two ways,  by   a) Natural Way &  by  b) Vaccination ;
a)     Natural Way – Natural immunity occurs  when you  get immune to a particular disease by contracting it  yourself, that is,  contracting it within your own body ;  In that case the anti-bodies   created in your  body to fight for that disease remain to be present in your body even after your recovery from that disease and protect you from that disease in future also ;  In this way when majority of the people in your society suffer from this disease, a  natural immunity at social level  or herd immunity  in your society  is built up ; But it is not preferable for the most obvious reason that to obtain herd immunity in this way  each  person of the majority number of people has to suffer from the disease  individually, which may turn up to be much costly to the society in terms of number of death toll and  excessive  pressure on medical infrastructure ; Besides,  one  may not know if one has contracted the illness or  if one is immune to it ;

b)     Herd Immunity by Vccination -  If the appropriate vaccine for that particular disease is already available in sufficient numbers  in that society, each of the majority  number of  persons,  may  get vaccinated individually and in this way herd  immunity  can also be obtained ;  That process is much safer but, only if the  vaccine is available ;

Herd Immunity  against Covid -19 :
          However, there are many reasons why herd immunity is not suitable to stop
          spreading of  this Novel  Corona Virus ;  The  main  reasons are as follows :-
·       Vaccinations are the safest way to obtain herd immunity in  a given population,  but  no Vaccine for Covid-19 has yet been discovered ;
·       The research for any anti-viral drug  is  also only  going on but still not in  hand  ;
·       Doctors do not know exactly why some people who contract this illness suffer from serious side effects while  the others do not ; 
·       Hospitals and healthcare infrastructure may get overburdened if many people contract  Covid-19 at the same time ; Sometimes it may go well beyond  the control of the Government ;
Indian  Context :
·       As the density of population in our country is very high, especially in urban slum area,  coupled with unhealthy living conditions,  it may not at all be suitable to risk our population in trying to obtain herd immunity by natural way ;
·       To obtain  herd immunity by  vaccination is not also possible at this moment as  no vaccine or any  antiviral drug  has yet been discovered ;
·       Hence,  in our country,  only  maintaining  the Social Distancing  and  proper  Sanitization at all levels  remain to be the only way out at this moment to fight against this Novel Corona Virus ;
Resources :
·        ‘What is Herd Immunity and Could it Help Prevent COVID-19 ?’
-        Written by Noreen Iftikhar  and Medically reviewed by  Stacy Sampson, D.O. ( ;  
·       ‘Is Herd Immunity Our Best Weapon Against  COVID-19 ?’
-        By  Jillian Monk,  May 5, 2020 ( ;  


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