Why did lockdown kill the coronavirus, but not the common cold?

Hand washing, social distancing, and disinfecting surfaces has been key to the quashing of the COVID-19 curve, but why hasn't it protected us from the common cold?

With winter in full swing, colds and sniffles seem to be as prevalent as ever.

Nikki Turner is the director of the Immunisation Advisory Centre and an associate professor in the Division of General Practice and Primary Health Care, University of Auckland.

She said it was inevitable that we would see the return of respiratory illnesses following the end of lockdown.

"What is really clear is that social distancing does work and we saw that with the lockdown, that many people were healthier and we had a lot less respiratory illnesses," she said.

"Exactly as you could expect, the moment we started moving out and about, mixing more, socialising more, we then have seen in the last couple of weeks more coughs, more colds, more respiratory illnesses."

Despite reports of much lower rates of flu infection than normal in the country, Turner said we would start seeing it again, as we were mixing more socially.

"Let's hope it's less, let's hope it's more mild, but it's definitely going to come."

Another factor to consider in the return of colds and flus was the season.

"We're not entirely clear why, but there's always a peak of respiratory illnesses in winter," she said.

"Some of that's because we get together more in confined spaces because it's cold and some of it's probably just the climate. But there is a direct effect of winter as well on the spread of respiratory illnesses."

Following lockdown, Turner said advice around testing for COVID-19 needed to change as we saw more coughs and colds - but that we still needed to remain aware of the prevalence of the virus around the world.

"We believe at the moment there is no COVID-19 spread in the community but we still have to have a high awareness. There are some symptoms particular to COVID-19, such as loss of taste or smell that might be different from a normal cough or cold."

She said if your symptoms felt different to those of a regular cold or flu to seek advice and get tested.

"We just need to keep a high level of suspicion, we do know that there's an awful lot of this virus around in the world, we're seeing that with the people coming through our quarantine, the amount that are coming through positive."

Public health experts at the University of Otago have called for an enquiry into the Government's response to the COVID-19 pandemic - a move which Turner said she supported.

"I think we're living in an extraordinary piece of history, we've never lived through this before. The fact that they make mistakes along the way is entirely what we'd expect," she said.

"Whether you call it an inquiry or an investigation, however you do it, I think at some stage, for any major piece of history like this, it's important to review what we've done."

Turner also had some advice for those dealing with respiratory illnesses during the winter.

"Stay at home, don't spread your bugs to other people, drink lots of fluids, get plenty of sleep. If you're unwell you can ring Healthline or ring your general practice - but ring first, before you enter so you don't spread your infection to others."

She said it was important to remember the flu vaccine was widely available in New Zealand currently and that people should access it both for themselves and for vulnerable people in the community.

"We'll get through the winter peak and we're all looking forward to a healthy spring and summer after that."

RNZ