The World Health Organization's (WHO) director-general, Tedros Adhanom Ghebreyesus, has called for countries to use their lockdown measures to slow the spread of COVID-19.

In the WHO daily press conference in Geneva, Ghebreyesus gave countries six tips to help fight the virus:

1. Expand, train and deploy the heathcare workforce

2. Implement a system to try to find every suspected case

3. Increase production, capacity and availability of testing

4. Adapt and equip facilities to treat and isolate patients

5. Develop a clear plan and process to quarantine patients

6. Refocus the government on suppressing and controlling the virus

"These measures are the best way to suppress and stop transmission, so that when restrictions are lifted, the virus doesn't resurge," he added.

Ghebreyesus said these measures are vital not only in countries where the virus is spreading at a fast rate, but also those who have very few cases so far. 

"More than 150 countries and territories still have fewer than 100 cases. By taking the same aggressive actions now, these countries have the chance to prevent community transmission and avoid some of the more severe social and economic costs seen in other countries. This is especially relevant for many vulnerable countries whose health systems may collapse under the weight of the numbers of patients we've seen in some countries with community transmission," he said.

COVID-19 worldwide cases currently top 470,000 with more than 21,000 deaths and Ghebreyesus said it's vital to try to slow these numbers as soon as possible.

The WHO director-general believes many countries squandered the first window of opportunity to slow the spread and no-one should waste the second one as the "window of opportunity is narrowing."