As countries across Europe tackle a surge in COVID-19 cases, the World Health Organization has urged nations to apply all tools at their disposal to avoid rampant community transmission.
Belgium, France, Germany and Italy, and the United Kingdom and Spain are among countries that have introduced new restrictions this week after a fast rise in cases.
The Spanish government has declared a state of emergency in Madrid and the surrounding region to fight the spike there.
It came as the high court in Madrid on Thursday turned down measures forced on the region by the central government.
Mike Ryan, executive director of WHO's Health Emergencies Programme, said that in many situations, new cases can be contained in the same way countries demonstrated at the very beginning of the pandemic.
He said the focus must be on shutting chains of transmission through tools such as case surveillance, case isolation and quarantining all contacts.
"The further you start behind, the harder it is to catch up," he said. He warned that when the disease becomes "very, very established, very, very intense", there are no options but to shutdown and lockdown.
Ryan cited the successful example of countries in the West Pacific and Southeast Asia, which reported the lowest level of new cases compared to other regions.
He said governments must support the battle with major investment. "Governments need to support really, really detailed surveillance, proper testing, contact tracing and these things," he said.
Unlike in China and other East Asian nations and regions, contact tracing and isolation are often not strictly enforced in many European countries.
Surveillance measures are sometimes regarded as an infringement of privacy and civil rights.
Ryan noted that one of the biggest problems in the pandemic response has been that "when governments differ, people die," referring to disputes between local and central governments in some European nations.
"So let's make sure we come together and make good decisions," Ryan said. He added that countries must do everything possible to avoid letting transmission become rampant at the community level.
Maria Van Kerkhove, the WHO's technical lead on COVID-19, also reiterated the importance of applying all tools.
"It's the implementation that is the challenge," she said.
She acknowledged the difficult balance of reopening society and suppressing transmissions, but said it's important to engage and empower the public and enable them to take the measures needed.
"If there is a stay at home order in place, they need to be supported," she said. "We need to be supportive of governments, supportive of communities and we need to be supportive of individuals because we are absolutely in this together," she said.