Covid-19 crisis Herd immunity among the foreign workers?
We may already have achieved herd immunity among the foreign workers. What does this mean?

During the past three weeks, over 20,000 foreign workers living in dormitories have been tested for the corona virus. I estimated that about 50% (i.e. 10,000 workers) are found to be positive in the test. They have the corona virus. 

What about the other 10,000 workers? Surely, when all the foreign workers are living together in the congested rooms and half has been infected, surely the other half must also be infected?

I believe that the other half have already been infected and are now immune from the virus. 

Why is this the case?

I was told that the test being carried out is the PCR test. It looks for the virus that are still active in the subject and returns a positive result. 

There is another test that looks for the antibody that is found in people that were infected before, and do not have the active virus now. These people are considered to be immune. This is the antibody or serology test. 

If the antibody test is done on the foreign workers that are negative on the PCR test, it is likely (in my opinion) that they will be found to have the antibody. They have already been infected before and are now immune.

I suggest that the ministerial task force carry out the antibody test on a sample of the foreign workers who are negative on the PCR test. 

The foreign workers that now have the virus are being isolated for 2 to 4 weeks. At the end of this period, they will be tested to be negative and can be released from isolation and return back to work, as they have achieved immunity.

Most of the 10,000 foreign workers who were found to be positive have a mild infection. They are kept in isolation facilities. Only a proportion need to be hospitalized. Only 2 workers need ICU. I wish them a safe recovery. 

By mid May, we may be able to declare that all the foreign workers have been infected and the virus has been contained. They would have achieve herd immunity.

I expect that this will be considered as a positive outcome for Singapore. it could be a case study on herd immunity. I may be wrong, but I hope that I am right.

Tan Kin Lian





 

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