Now that COVID-19 infection rates and deaths have not disappeared but are at relatively low levels in the US, attention is turning to the significant proportion of the population who continue to report COVID symptoms long after initial infection. This condition, which has come to be known as ‘long COVID’, has yet to be clearly identified as a clinical condition, but is defined by the World Health Organization (WHO) as the continuation or development of new symptoms three months after the initial infection, with these symptoms lasting for at least two months with no other explanation.
The recency of long COVID, together with difficulties in precisely defining it (Rando et al. 2021), mean uncertainty persists regarding its incidence and consequences (Landman 2022). Notwithstanding these issues, a consensus is emerging that long COVID is a common condition among those infected with the virus, although its incidence varies across demographic groups. It often comes with multiple symptoms which can be severe and affect both cognitive and physical function. For instance, in their systematic review article, Davis et al. (2023) say that more than 200 symptoms have been identified, with impacts on multiple organ systems.
Since April 2020, the US Census Bureau has been running a Household Pulse Survey (HPS) tracking the incidence, correlates, and consequences of COVID infection and the effectiveness of the vaccine programme in combating it. We have reported on that previously (Blanchflower and Bryson 2022). However, since June 2022 the Bureau has incorporated specific questions to capture long COVID. In a new paper (Blanchflower and Bryson 2023) exploiting these data, we find 14% of the 460,000 Americans in the survey reported suffering long COVID at some point, half of whom reported it at the time of the survey – so long COVID often goes away.
The incidence of long COVID varies markedly across the US – from 11% in Hawaii to 18% in West Virginia – and is higher for women than men, among Whites compared with Blacks and Asians, and declines with rising education and income. It peaks in midlife in the same way as negative affect.
We find that ever having had long COVID is strongly associated with negative affect as indicated by anxiety, depression, worry and a lack of interest in things. The effect is larger among those who currently report long COVID, especially if they report severe symptoms.
In contrast, those who report having had short COVID report higher wellbeing than those who report never having had COVID.
Long COVID is also strongly associated with physical mobility problems, such as walking or climbing stairs, and with self-care such as problems dressing and bathing. It is also associated with cognition difficulties such as remembering or concentrating, and difficulties understanding or being understood. Again, the associations are strongest among those who currently report long COVID, while those who said they had had short COVID have fewer physical and mental health problems than those who report never having had COVID.
The possibility exists that some of the impact of long COVID on mobility and cognition could arise due to poor mental health. Indeed, there is evidence from Wang et al. (2022) that prior psychological distress before COVID infection is associated with risk of COVID-19-related symptoms lasting four weeks or longer. However, while scoring high on negative affect is strongly and positively associated with physical and mental health problems, long COVID continues to be strongly associated with physical and mental health problems having controlled for negative affect.
Regardless of COVID status, those who have been vaccinated experience better wellbeing, and fewer physical and mental health difficulties, underscoring the importance of this public health programme.
Blanchflower, D G and A Bryson (2023), “Long COVID in the United States’, NBER Working Paper No. 30988
Blanchflower, D G and A Bryson (2022), “COVID and Mental Health in America”, PLoS ONE 17(7): e0269855
Davis, H E, L McCorkell, J M Vogel and E J Topol (2023), “Long COVID: major findings, mechanisms and recommendations”, Nature Reviews Microbiology 21: 133-146
Landman, K (2022), “Four questions about long COVID experts wish they could answer”, Vox.com.
Rando H M, T D Bennett, J B Byrd et al. (2021), “Challenges in defining long COVID: striking differences across literature, electronic health records, and patient-reported information”, medRxiv, published online 26 March.
Wang S, L Quan, J E Chavarro et al. (2022), “Associations of depression, anxiety, worry, perceived stress, and loneliness prior to infection with risk of post–COVID-19 conditions”, JAMA Psychiatry 79(11): 1081–1091.