Which Antibodies give you Immunity ?

Which Antibodies give you Immunity ?

      HEADLINES:

Which antibodies give immunity?

      WHY IN NEWS:

Out of those found infected with novel coronavirus in a serorsuvey in Pune, 85% developed neutralising antibodies.

SYLLABUS COVERED: GS 3:Health:Diseases

      LEARNING: 

For PRELIMS you need to understand the connection between serosurvey’s and neutralising anti-bodies.

For MAINS take a note on concept of immunity in your Mains book.Let us dive in !

      ISSUE: 

A new study in Pune has revealed that nearly 85% of the people infected with novel coronavirus in a serosurvey, conducted earlier, had developed neutralising antibodies.

THE PROGRESS TOWARDS ‘HERD IMMUNITY’

  • About 51% of those tested were found to have antibodies.
  • Among these, 85% had neutralising antibodies.
  • In other words, these people had developed immunity against the disease.

It is sometimes thought that everyone infected with a disease-causing virus, and recovers, becomes immune to the disease, because they build antibodies against it.

  • But that is not the case.It is not true.

THE CONCEPT OF IMMUNITY

While the creation of antibodies is necessary for the recovery process, it does not guarantee immunity against a future attack from the same virus. 

IMMUNNITY
Immunity comes from what are known as “neutralising” or “protectiveantibodies.

  • Neutralising antibodies, like other antibodies that are created to fight the disease, are nothing but proteins.
  • These are a small subset of the disease-specific antibodies that are generated once an infection has occurred.
  • The neutralising antibodies become special because they have the ability to thwart the entry of the same virus inside human bodies in the future.
  • The other antibodies help in fighting off the virus once the infection has already happened.
  • Serosurveys, like the ones that have been conducted in Delhi, Mumbai, Pune and other cities, only look for the presence of antibodies in people.
  • Their purpose is to find out whether a person has been infected with the virus or not.

Through random testing of people, serosurvey estimates the extent of spread of the disease, or prevalence, in a population group.

  • Detection of disease-specific antibodies confirms that the person had been infected with the virus in the past.
  • A further test needs to be carried out to detect the presence of neutralising antibodies.
  • This is what has happened in the case of Pune, the only study that has looked for neutralising antibodies.

CASE STUDY : PUNE

  • The serosurvey was conducted on about 1,650 individuals in five prabhags (each consisting of three to four municipal wards) of Pune.
  • The study shows that while a majority of infected people do develop immunity.

Also there was a significant proportion (15% in this case) who do not become immune even after getting infected. 

  • That would mean that they are at risk of reinfection.
  • Although very few cases of reinfection have been documented in the current epidemic, it cannot be ruled out.
  • That is why people who have recovered from the disease are also urged to continue to take protective measures such as practice physical distancing and wearing a mask.

Which Antibodies give you Immunity ?

Which Antibodies give you Immunity ?

IS IMMUNITY PERMANENT?

  • In the case of the novel coronavirus, it is not yet known whether the immunity acquired through natural infection lasts for weeks, months or years.

The longevity of the immunity against a disease depends on a variety of factors, including the quantity of neutralising antibodies generated.

  • In the Pune study, About half the people had generated high levels of these antibodies, while the others had relatively low levels.
  • Those with a high quantity of neutralising antibodies could be expected to remain immune to the disease for a longer time.

RATE OF DECLINE

It is also important to understand that neutralising antibodies, as also other antibodies, decrease with time.
 

  • The rate of decline varies in different diseases and individuals.
  • So, in the same time that people with low neutralising antibodies see their immunity becoming ineffective, those with higher levels could still have enough to continue to fend off the virus.

Also, scientists do not fully understand why certain people do not generate neutralising antibodies. 
 

  • Their immune system seems to be working fine, but for whatever reason they do not create those specific proteins.

The longevity of the immunity against a disease depends on a variety of factors, including the quantity of neutralising antibodies generated.

WHAT ABOUT VACCINE-INDUCED IMMUNITY?

  • As in the case of naturally-acquired immunity, we do not know, as of now, how long the immunity provided by a vaccine would last against the novel coronavirus.

The level of immunity generated by a vaccine is usually expected to be longer and better.

  • That is because the vaccine is designed to trigger a strong immune response with a high fraction of neutralising antibodies.
  • But since the vaccines currently under production have been under trial for only a few months, the duration of immunity they provide is not known.
  • If the vaccines that are eventually approved for use do not provide long-lasting immunity, they are unlikely to have high acceptance among the general public.

      IASbhai WINDUP: 

IS PUNE APPROACHING ‘HERD IMMUNITY’?

  • The serosurvey was conducted on about 1,650 individuals in five prabhags (each consisting of three to four municipal wards) of the city.

RESULT
About 51% of those who were tested, or about 850, were found to have antibodies

  • Of those with antibodies, now 85% have been found to have developed immunity.
  • Disease prevalence in Pune, like any other city, is not uniform.
  • The findings of the study could be applied well in the small population groups .

The study is important because it shows that wherever there was high seropositivity, incidence rate has fallen subsequently

SUGGESTED READING : COVID-19 IMMUNISATION PROGRAMME 
     SOURCES:   IE  | Which Antibodies give you Immunity ?

 

DISCOVER MORE : GENERAL STUDIES-III

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