Nowadays, many methods were used for covid-19 diagnoses like RT-PCR, antigen, or antibody test. Despite its unaffordability, the RT-PCR remains a confirmatory one. As a point of care, either antigen or antibody test is preferred to address remote and wider communities. Currently, covid-19 vaccination is undergone around the globe. So, what will be the challenges to our diagnosis of SARS-CoV-2 after vaccination? What is the diagnostic validity of the covid-19 antigen test when compared to RT-PCR detection before and after vaccination?
That would depend on the nature of the vaccine and the principle behind the test employed. If the vaccine triggers humoral immunity, then that could interfere with the outcome of antibody testing. However, the RT-PCR protocol is not gold-standard for nothing. I believe the experts would have considered these concerns.
Considerations for diagnostic COVID-19 tests
https://www.nature.com/articles/s41579-020-00461-z
However, in comparison with rtPCR, rapid antigen detection tests lack sensitivity, and owing to the increased risk of false-negative results, they are considered as an adjunct to rtPCR tests16,17.
Mertens, P. et al. Development and potential usefulness of the COVID-19 Ag Respi-strip diagnostic assay in a pandemic context. Front. Med. 7, 225 (2020).
Mak, G. C. et al. Evaluation of rapid antigen test for detection of SARS-CoV-2 virus. J. Clin. Virol. 129, 104500 (2020).
Hello Edosa Kifle
The mRNA-based vaccines are made of a small region of the viral genome which enters the host cell and tricks the cell into making the specific viral protein (spike protein) against which an immune response is generated. RNA molecules are unstable, and they are even degraded by enzymes that target them. So, mRNA vaccines will not have any impact on RT-PCR test after vaccination.
Moreover, the proteins that are produced after vaccination are not expressed in the respiratory tract which is sampled for RT-PCR and antigen testing.
However, antibody testing may come positive after vaccination. But antibodies formed after vaccination will be only for that part of the virus which has been incorporated in the vaccine. For instance, S protein is the main protein which has been used as a target in Covid-19 vaccines. So, the test to detect antibodies against the S protein will have to be used to confirm whether the vaccination has elicited an immune response.
In Covid-19 infected individuals, antibodies will be detected against different parts of the virus for which different serological tests are used.
Therefore, vaccine should not have any effect on Covid-19 diagnosis whether it be RNA, antigen, or antibody
Best Wishes.
PCR test are more reliable. Antigen tests are not as reliable, but they are faster.
There is no effect of vaccination on the diagnostic tests for COVID-19.
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