Public health management during COVID-19

The COVID-19 pandemic is a public health emergency. Learn about the public health management actions we are taking, and your responsibilities as a healthcare provider.

Serological testing for immunity

It is not recommended to test for anti-spike antibodies or neutralising antibodies to demonstrate immunity against SARS-CoV-2 in vaccinated people. This is because an immune correlate of protection has not yet been established for SARS-CoV-2 infection.1

Impact of vaccination on future COVID-19 testing

Receiving a COVID-19 vaccine will not affect the results of nucleic acid (PCR) testing or rapid antigen testing for diagnosis of SARS-CoV-2 infection.

Because Comirnaty (Pfizer), Spikevax (Moderna), Vaxzevria (AstraZeneca), and Nuvaxovid (Novavax) COVID-19 vaccines encode the spike protein of SARS-CoV-2, vaccination may affect any subsequent serological diagnostic testing. This may result in detection of antibody to the spike protein. Vaccination will not affect the results of anti-nucleocapsid antibody testing.

Isolation or testing for COVID-19 following vaccine-related adverse events

If a person has received a COVID-19 vaccine in the past 48 hours and they develop symptoms such as fever, headache, fatigue or other systemic symptoms, they do not necessarily need to be tested for SARS-CoV-2 infection or be isolated.

If a person who has received a vaccine develops typical vaccine-related adverse events (see Adverse events – clinical guidance) and they do not have any respiratory symptoms (including loss of smell), it is more likely that they have an expected vaccine response.

However, vaccine-induced protection is not immediate. It is possible that SARS-CoV-2 could be contracted within several days before or after vaccination. This would not constitute vaccine failure.

Local public health guidance should be followed regardless of the person’s COVID-19 vaccination history. Criteria for SARS-CoV-2 testing vary, and depend, in part, on local epidemiology and outbreak management.

For Pfizer, the median time of onset of systemic adverse events was 1 to 2 days after vaccination. Symptoms resolved in a median of 1 day.

For Moderna, the median onset of systemic adverse events was 0 to 1 days after vaccination for most participants (70.2%). Symptoms continued for about 3 days on average.2 

For AstraZeneca, local or systemic solicited adverse events were most commonly reported on day 1 after vaccination. Symptoms generally resolved within a few days.

For Novavax, the median time of onset of systemic adverse events was 1-2 days after vaccination. Symptoms resolved in a median of 2 days or less.

Post-exposure prophylaxis

COVID-19 vaccines are not recommended for post-exposure prophylaxis. No data are available to support such use.

The median incubation period for SARS-CoV-2 is 5 to 6 days (with a range of 1 to 14 days in most people). Vaccination after exposure is unlikely to generate sufficient immunity within this period to prevent infection in people who have not been vaccinated.

Local public health authorities may recommend prioritising COVID-19 vaccination for certain populations related to local outbreaks or settings with community transmission of COVID-19. For the latest information, see the CDNA National guidelines for public health units on COVID-19.

Further reading

  1. Poland GA, Ovsyannikova IG, Kennedy RB. SARS-CoV-2 immunity: review and applications to phase 3 vaccine candidates. The Lancet 2020;396:1595-606.
  2. Baden LR, El Sahly HM, Essink B, et al. Efficacy and Safety of the mRNA-1273 SARS-CoV-2 Vaccine. New England Journal of Medicine 2021;384:403-16.
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