The World Health Organisation has given Long Covid a formal definition, setting out agreed symptoms and timeframes to help spot the common post-Covid condition.
In its definition, the WHO states Long Covid can be seen three months from the onset of Covid-19, with at least two months of symptoms that cannot be explained by an alternative diagnosis.
"Common symptoms include fatigue, shortness of breath, cognitive dysfunction but also others which generally have an impact on everyday functioning," the definition says.
"Symptoms may also fluctuate or relapse over time."
New Zealand experts are welcoming the formal definition, that can help doctors assess and diagnose Long Covid.
"We hope that by having a clinical case definition, that more patients will be listened to, and taken seriously when they seek the medical care they so desperately need," University of Auckland cellular immunologist and senior research fellow Dr Anna Brooks says.
"It is incredibly distressing to hear that many of those that meet this criteria here in Aotearoa have given up seeking medical care due to the trauma of being 'gas-lit', or dismissed by their doctors.
"The odds of getting Long Covid following two vaccine doses is very low. Given Long Covid does not discriminate and can affect all ages, it is even more critical that we protect those who are most vulnerable – those who cannot be vaccinated and children who are not eligible – by ensuring we reach high vaccination rates."
Infectious disease specialist and senior lecturer at the University of Auckland, Dr Stephen Ritchie, said the effects of Long Covid could be "devastating".
"Many New Zealanders already suffer from this problem and many, many more will in the future," Ritchie said.
"At present, the best way to avoid post Covid-19 is to get fully vaccinated – a UK study showed that vaccination reduced the risk of having ongoing symptoms after one month by a half."