ABSTRACT
We report the earliest known cluster of SARS-CoV-2 infection so far reported, which occurred in New Zealand in late February 2020. The cluster includes one confirmed and five probable cases. The cluster was identified while investigating a weak positive nasopharyngeal swab (NPS) polymerase chain reaction (PCR) test that was returned by a male in his 60s in September 2020. The PCR result, combined with a clear clinical and epidemiological history of a COVID-19 like illness in late February 2020, prompted serological testing. SARS-CoV-2 IgG antibodies were detected and supported historical infection. Serology was also reactive for five close contacts who had also experienced a COVID-19 like illness in February 2020. Combined case histories and investigations suggest that this local cluster was import related, with the index case identified as a family member visiting from Italy in February. Case investigation also suggests this cluster was active in New Zealand prior to any previously documented local cases, indicating that SARS-CoV-2 was present and local transmission was occurring earlier than initially suspected. A weak positive PCR result, six months after acute infection, supports international evidence that SARS-CoV-2 genetic material can be detected for several months after initial COVID-19 infection, and that this is not necessarily indicative of infectivity.
ABSTRACT
Stringent nonpharmaceutical interventions (NPIs) such as lockdowns and border closures are not currently recommended for pandemic influenza control. New Zealand used these NPIs to eliminate coronavirus disease 2019 during its first wave. Using multiple surveillance systems, we observed a parallel and unprecedented reduction of influenza and other respiratory viral infections in 2020. This finding supports the use of these NPIs for controlling pandemic influenza and other severe respiratory viral threats.