An epidemiological look at 1,981 women who reported a positive SARS-CoV-2 test found that those with pre-infection healthy lifestyle had a substantially lower "risk" of the post–COVID-19 condition known as 'long COVID.' 

It is just correlation but it brings to light concerns about how much of an impact co-morbidities and lifestyle had on the effects of SARS-CoV-2 and lingering effects. And how much benefit health care workers would have derived from healthier lifestyles prior to the pandemic.

The prospective cohort study totaled 32,249 women in the Nurses’ Health Study II cohort, which surveyed lifestyle habits in 2015 and 2017.  Of the 1,981 final women included, the age range was 55 to 75 with a mean of 64.7 years , nearly 100 percent were caucasian and nearly half were active health care workers.

Among them, 44 percent reported Long COVID.  Compared to those with no healthy lifestyle behaviors, those with 5 to 6 had 49 percent lower risk (RR, 0.51; 95% CI, 0.33-0.78) of PCC. 
Those lifestyle factors included healthy body mass index (BMI, 18.5-24.9; calculated as weight in kilograms divided by height in meters squared), never smoking, at least 150 minutes per week of moderate to vigorous physical activity, moderate alcohol intake (5 to 15 g/d), high diet quality (upper 40% of Alternate Healthy Eating Index–2010 score), and adequate sleep (7 to 9 h/d).

In a model mutually adjusted for all lifestyle factors, BMI and sleep were independently associated with risk of PCC (BMI, 18.5-24.9 vs others, RR, 0.85; 95% CI, 0.73-1.00, P = .046; sleep, 7-9 h/d vs others, RR, 0.83; 95% CI, 0.72-0.95, P = .008).

If these associations were causal, and this is only correlation, 36.0% of Long COVID cases would have been prevented if all participants had 5 to 6 healthy lifestyle factors (population attributable risk percentage, 36.0%; 95% CI, 14.1%-52.7%). Results were comparable when Long COVID was defined as symptoms of at least 2-month duration or having ongoing symptoms at the time of Long COVID assessment.

Another confounder along with the limited pool is that COVD-19 was confirmed by test while symptoms much later were self-reported.