[watchfirst9]

More likely because of natural immunity. I think many people got it but didn't report since not sick. 

But all this will likely change with new variant Omicron. Then Sinovac and Sinopharm will perform better according to Dr Gabriel Oon because these got all the 7 antigens of the virus.

Hope for the best.

Likely due to many companies require staff to test at least once every week.
Natural immunity is not possible for mutation virus, influenza is good example.

Omicron which has many mutations on the protein spike,
will weaken all vaccines, especially more on the mRNA ones,
as they teach only part of protein spike. 

Time to widely use more nasal inhibitor spray 
https://www.thestar.com.my/lifestyle/hea...9-included

https://menafn.com/1103042935/Vaccine-na...r-on-virus

https://www.pharmacytimes.com/view/clini...f-covid-19

and internasal vaccine.