Antonio Guterres said ‘when countries go in their own direction, the virus goes in every direction’.
More than 1.5 million people have died worldwide due to coronavirus, a third of them in the last two months alone.
Nearly 65 million people have been infected by COVID-19 and in the past week, more than 10,000 died on average every day.
The figures underscore the severity of the pandemic amid the announcement of a vaccine rollout in the UK.
United Nations Secretary-General Antonio Guterres warned on Thursday the world could be fighting the aftershocks of the COVID-19 pandemic for decades to come even if vaccines are quickly approved.
However, governments around the world have been enforcing stricter restrictions and lockdowns given the rising numbers.
On Wednesday, Italian Prime Minister Giuseppe Conte announced new lockdown measures ahead of the Christmas period due to fears of a further spread of the virus.
Movements across regions in Italy will be banned from December 21 to January 6, while people will not be allowed to move across towns on December 25 and 26.
A curfew from 10pm (21:00 GMT) to 5am (04:00 GMT) remains across the whole country, but will be extended to 7am (06:00 GMT) for January 1.
The United States continues to witness a surge in infections with record daily deaths and hospitalisations this week.
On Wednesday, the country reported more than 203,300 new cases, at least 2,700 deaths and 100,000 hospitalisations in the past 24 hours.
President-elect Joe Biden said he will make masks mandatory during his first 100 days in office.
A partial lockdown will begin this weekend in the Gaza Strip after COVID-19 infections spiked in the densely populated territory.
Mosques and most schools will be closed during the day although many businesses will be allowed to remain open until a nighttime curfew forces residents to stay at home.
There will be a full closure at weekends.
Interior ministry spokesman Eyad Al-Bozom told reporters authorities were also considering moving to a complete lockdown if needed.
South Korea said it is considering tightening its social distancing rules as it reported 629 new coronavirus cases on Friday, the most since the first wave of infections in the country peaked in late February.
Prime Minister Chung Sye-kyun said the situation was critical as infections continued to rise at an alarming rate despite the reimposition of social-distancing rules late last month, and added that the government would decide on Sunday whether to upgrade restrictions.
Authorities are concerned that university entrance exams which nearly half a million students sat on Thursday could prove to be another source of infections.
Britain will pay individuals who suffer any severe side-effects from COVID-19 vaccines under an existing programme, ahead of a rollout of Pfizer and BioNTech’s vaccine in the country.
COVID-19 will be added as a “precautionary step” to the list of diseases covered for potential liabilities under the Vaccine Damage Payments Scheme (VDPS).
Under the scheme, individuals are entitled to a lump sum capped at 120,000 pounds ($161,676) if they can prove to have been seriously disabled as a result of a vaccination.
Iran said its novel coronavirus infections surpassed one million cases on Thursday, as the authorities consider easing restrictions in many parts of the country.
The country has recorded 1,003,494 COVID-19 infections since announcing its first cases in February, ministry spokeswoman Sima Sadat Lari said on state television.