The world continues to grapple with the COVID-19 pandemic, with vaccine mandates still a hot topic despite the endorsement from public health experts.

But last week, it wasn't just the typical cast of vaccine dissenters who voiced opposition to mandates. Two Democrats and a key World Health Organization medical doctor also dealt a bit of a blow to President Joe Biden's and other world leaders' plans.

On Wednesday, Democratic Sens. Joe Manchin of West Virginia and Jon Tester of Montana voted against President Biden’s vaccine-or-test mandate for large businesses, joining every Republican senator in a 52-48 vote. The vote is considered symbolic since it has very little chance of passing the Democrat-controlled House.

The mandate orders businesses with at least 100 workers to obtain proof of vaccination from employees by Jan. 4 or subject them to weekly testing and masking. 

Manchin, who has pushed for Americans to get vaccinated, co-sponsored the bill. He said the mandate is federal overreach.

Americans mostly disagree with Manchin. A Gallup poll in September found that 58% of Americans are in favor of large companies requiring their employees to get vaccinated against COVID, or be tested for it weekly.

Europe has also seen pushback on vaccine mandates. 

On Tuesday, Dr. Hans Kluge, the WHO's Europe director, said that compulsory vaccinations should be an “absolute last resort." 

"The effectiveness of mandates is very context-specific. What is acceptable in one society and community may not be effective and acceptable in another."

Kluge’s remarks come just as several European countries are grappling with winter COVID surges and questions over the Omicron variant and its risks. British Prime Minister Boris Johnson on Sunday said the nation faces a “tidal wave” of infections from the Omicron variant.

On Saturday, roughly 45,000 protestors in Vienna rallied against mandatory COVID vaccines.

Kluge acknowledged that some countries have sidelined concerns over vaccine mandates in favor of the overall benefit they presumably bring.

But Kluge said governments need to reach out to the communities involved, consider the impact on public trust, and whether any social health inequities will be exacerbated before applying a compulsory vaccination mandate.

Kluge conceded that mandates “have proven effective in some environments to increase vaccine uptake.” However, he also said, “the effectiveness of vaccine mandates is very context-specific.”

Vaccines have been proven to greatly reduce the risk of severe infection, hospitalization and death from the COVID virus, but research has shown that vaccine immunity wanes after around six months and that they are not 100% effective at reducing transmission.

Kluge said vaccine mandates should never contribute to increasing social inequalities in access to health and social services.

“Any measure that might restrict a right or a movement of a person, such as lockdowns or mandates, needs to be sure that mental health and well-being is cared for,” Kluge said during the same briefing.

Kluge’s remarks follow those of European Commission Chief Ursula von der Leyen who recently said it was time to “think about mandatory vaccination” in the European Union, where individual states can impose vaccine mandates.