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Explainer: Reaching Herd Immunity In A Viral Pandemic

As per the experts, there are two pathways to herd immunity – natural infection, when a large number of people have had a disease and recovered; or vaccination, which can provide widespread immunity faster and more reliably

Explainer: Reaching Herd Immunity In A Viral Pandemic
Highlights
  • There are two pathways to herd immunity: natural infection or vaccination
  • How a vaccine is distributed has implications for effectiveness: Experts
  • Epidemiologists don't think early vaccines will have 100% efficacy

Sydney: The novel coronavirus pandemic has brought “herd immunity” to the public consciousness, kindling hope the phenomenon can help slow or even end the outbreak. Herd immunity refers to a large portion of a community developing a degree of immunity to a virus, thereby reducing person-to-person spread. As a result, the whole community gains protection, not just those who are immune.

NATURAL INFECTION VS VACCINATION

There are two pathways to herd immunity: natural infection or vaccination.

Natural infection refers to when a large number of people have had a disease and recovered. However, the extent of protection via natural infection is unknown with the new coronavirus. Moreover, more people would die while waiting for herd immunity than if a vaccine was produced.

Also Read: Coronavirus Outbreak Explained: Here’s India’s Current COVID-19 Status, Using The ‘R’ Rate Method

The risk is not acceptable, said Catherine Bennett, epidemiology chair in the Faculty of Health at Melbourne’s Deakin University. We can’t afford to have people infected to reach herd immunity when we know so little about the longer-term effects.

Vaccination can provide widespread immunity faster and more reliably.

There is no vaccine for COVID-19 – the disease caused by the novel coronavirus – though trials at different stages are underway around the world. It usually takes several years for a vaccine to be identified, tested, produced and distributed for public use. Vaccine makers hope to dramatically compress that timeline for COVID-19 through faster trials and by manufacturing at scale even before products have proved successful.

Experts believe if no other measures are taken, herd immunity could kick in when 50% to 70% of a population gains immunity through vaccination. The precise level depends on the vaccine’s efficacy rate, which experts say will be 70% at best.

BALANCING VACCINE DISTRIBUTION

How a vaccine is distributed has implications for effectiveness. If shared unevenly – for example, if the wealthy have greater access than those in poorer locations – that would create safe clusters but leave large areas of susceptible people.

In the early stages of distribution, higher priority may be given to healthcare workers and others on front lines, or those considered most vulnerable – a process known as targeted vaccination. That risks missing people who might be considered “super spreaders”, such as public transport workers.

We need to be sure that we spread the vaccine equitably through the population, said Joel Miller, a senior lecturer in applied mathematics at La Trobe University in Melbourne, who uses mathematical models to help governments and non-profit organisations formulate policies to control infectious diseases.

Also Read: Why Is India Experiencing Spike In COVID-19 Cases? Dr Randeep Guleria OF AIIMS Explains

MOVEMENT RESTRICTIONS

The movement of people also has implications for the spread of a virus.

At lower vaccination levels, the number of people who eventually become infected is similar in a group of people who mix and travel widely, and a group of people who are relatively static. However, the spread is much slower in a static population, hence governments worldwide imposing lockdown measures.

Even when a high percentage of the population is vaccinated, infection numbers can be reduced further if people refrain from travel.

WHILE WE WAIT

The new coronavirus is spread primarily via droplets expelled when a person coughs, sneezes or even talks.

Until a vaccine is developed, wearing masks, physical distancing and hand hygiene can help reduce transmission and contribute to creating herd immunity.

Epidemiologists largely agree that a combined approach is critical given early vaccines brought to market will likely not have 100% efficacy.

It’s about adding layers, said Deakin University’s Bennett. It gives us extra protection from community spread. The situation is very much better in places where a combination of measures is being used.

Also Read: Coronavirus Explained: What Are Super-Spreaders And How Are They Responsible For COVID-19 Transmission?

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)

NDTV – Dettol Banega Swasth India campaign is an extension of the five-year-old Banega Swachh India initiative helmed by Campaign Ambassador Amitabh Bachchan. It aims to spread awareness about critical health issues facing the country. In wake of the current COVID-19 pandemic, the need for WASH (WaterSanitation and Hygiene) is reaffirmed as handwashing is one of the ways to prevent Coronavirus infection and other diseases. The campaign highlights the importance of nutrition and healthcare for women and children to prevent maternal and child mortality, fight malnutrition, stunting, wasting, anaemia and disease prevention through vaccines. Importance of programmes like Public Distribution System (PDS), Mid-day Meal Scheme, POSHAN Abhiyan and the role of Aganwadis and ASHA workers are also covered. Only a Swachh or clean India where toilets are used and open defecation free (ODF) status achieved as part of the Swachh Bharat Abhiyan launched by Prime Minister Narendra Modi in 2014, can eradicate diseases like diahorrea and become a Swasth or healthy India. The campaign will continue to cover issues like air pollutionwaste managementplastic banmanual scavenging and sanitation workers and menstrual hygiene

World

24,20,23,922Cases
20,36,06,535Active
3,34,95,808Recovered
49,21,579Deaths
Coronavirus has spread to 195 countries. The total confirmed cases worldwide are 24,20,23,922 and 49,21,579 have died; 20,36,06,535 are active cases and 3,34,95,808 have recovered as on October 21, 2021 at 4:33 am.

India

3,41,27,450 18,454Cases
1,78,831 733Active
3,34,95,808 17,561Recovered
4,52,811 160Deaths
In India, there are 3,41,27,450 confirmed cases including 4,52,811 deaths. The number of active cases is 1,78,831 and 3,34,95,808 have recovered as on October 21, 2021 at 2:30 am.

State Details

State Cases Active Recovered Deaths
Maharashtra

65,96,645 1,825

29,333 1,075

64,27,426 2,879

1,39,886 21

Kerala

48,79,790 11,150

83,333 2,476

47,69,373 8,592

27,084 82

Karnataka

29,84,484 462

9,103 26

29,37,405 479

37,976 9

Tamil Nadu

26,90,633 1,170

14,058 268

26,40,627 1,418

35,948 20

Andhra Pradesh

20,61,810 523

5,566 88

20,41,924 608

14,320 3

Uttar Pradesh

17,10,058 11

112 6

16,87,048 17

22,898

West Bengal

15,82,813 867

7,491 63

15,56,315 795

19,007 9

Delhi

14,39,466 25

310 12

14,14,066 37

25,090

Odisha

10,36,532 559

4,387 106

10,23,849 451

8,296 2

Chhattisgarh

10,05,735 34

185 3

9,91,979 36

13,571 1

Rajasthan

9,54,393 1

38 0

9,45,401 1

8,954

Gujarat

8,26,340 14

176 9

8,16,077 22

10,087 1

Madhya Pradesh

7,92,709 9

82 3

7,82,104 6

10,523

Haryana

7,71,116 15

133 7

7,60,934 8

10,049

Bihar

7,26,036 3

30 12

7,16,345 15

9,661

Telangana

6,69,556 191

3,968 28

6,61,646 162

3,942 1

Assam

6,07,427 308

3,610 25

5,97,859 282

5,958 1

Punjab

6,02,113 32

232 16

5,85,331 15

16,550 1

Jharkhand

3,48,486 25

142 14

3,43,209 11

5,135

Uttarakhand

3,43,773 8

176 1

3,36,199 6

7,398 1

Jammu And Kashmir

3,31,299 78

800 3

3,26,070 80

4,429 1

Himachal Pradesh

2,21,936 110

1,394 46

2,16,815 64

3,727

Goa

1,77,706 47

597 23

1,73,755 70

3,354

Puducherry

1,27,521 42

461 29

1,25,208 71

1,852

Manipur

1,22,970 71

1,360 2

1,19,706 66

1,904 3

Mizoram

1,15,207 741

10,263 505

1,04,548 1,243

396 3

Tripura

84,351 2

95 7

83,440 9

816

Meghalaya

83,158 79

761 21

80,958 58

1,439

Chandigarh

65,312 2

24 1

64,468 3

820

Arunachal Pradesh

55,043 12

138 7

54,625 19

280

Sikkim

31,800 17

175 6

31,232 22

393 1

Nagaland

31,659 18

255 8

30,728 10

676

Ladakh

20,886 3

34 0

20,644 3

208

Dadra And Nagar Haveli

10,676

2 2

10,670 2

4

Lakshadweep

10,365

0 0

10,314

51

Andaman And Nicobar Islands

7,646

7 1

7,510 1

129

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1 Comment

1 Comment

  1. Peter Smith

    March 16, 2021 at 8:06 pm

    The way you have provided detailed tips, opinions, and discussions about TheHerd immunity, and the guidance you provided, it’s imperative. Reading this post will make everyone feel better about “Covid-19“…

    Thank You

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