Time to resolution of Long COVID symptoms and the associated factors among the people infected with SARS-CoV-2 during the 3rd wave of COVID-19 in Zambia: A prospective quantitative study

This study was conducted over 24 months (September 2021-Agust, 2023) to determine the time to resolution of Long COVID symptoms and the associated factors among people infected with SARS-CoV-2 during the 3rd wave (June - August, 2021) of COVID-19 in Zambia. Participants comprised a cohort of 303 people randomly sampled from 7 healthcare facilities from Lusaka and Southern provinces. Demographic and clinical data were collected at baseline and at a monthly interval from participants’ clinical records and interview. Descriptive analysis was conducted to summarise respondent demographic and clinical characteristics.  Survival analysis (Kaplan Meier model) was conducted to determine the median time to symptom resolution, generate survival curves and the risk table. A Poisson model was fitted to compute the crude incident rate of recovery. Cox-Proportional Hazards regression analysis was conducted to determine the univariate and multivariate association between the covariates and the time to resolution of symptoms. Crude and adjusted hazard ratios, 95% confidence intervals and p-values were computed.  A total of 236 events occurred during the follow- up period; the crude incidence rate was 1, 575.6 events per 1000 person years (95%CI: 1,363.2 - 1,784.4). The median time from diagnosis of Long COVID symptoms to resolution was 6 (IQR: 5-8) months.  Vaccination status was significantly associated with the time to resolution of  symptoms (aHR= 1.71, 95% CI: 1.02 - 2.86, p=0.04) after adjusting for age, number of children, occupation, pre-existing medical conditions, number of vaccine doses and hospital admission. Other variables did not show statistically significant association with the time to resolution of symptoms (p>0.05). These findings suggest that vaccination is associated with a shorter time to resolution of Long COVID symptoms. Netherless, causation can not be ascertained due to the observational design of the study. A study with an experimental design is needed to establish the causal relationship.