Long-COVID Symptoms in Individuals Infected with Different SARS-CoV-2 Variants of Concern: A Systematic Review of the Literature

Abstract

The association of SARS-CoV-2 variants with long-COVID symptoms is still scarce, but new data are appearing at a fast pace. This systematic review compares the prevalence of long-COVID symptoms according to relevant SARS-CoV-2 variants in COVID-19 survivors. The MEDLINE, CINAHL, PubMed, EMBASE and Web of Science databases, as well as the medRxiv and bioRxiv preprint servers, were searched up to 25 October 2022. Case-control and cohort studies analyzing the presence of post-COVID symptoms appearing after an acute SARS-CoV-2 infection by the Alpha (B.1.1.7), Delta (B.1.617.2) or Omicron (B.1.1.529/BA.1) variants were included. Methodological quality was assessed using the Newcastle–Ottawa Scale. From 430 studies identified, 5 peer-reviewed studies and 1 preprint met the inclusion criteria. The sample included 355 patients infected with the historical variant, 512 infected with the Alpha variant, 41,563 infected with the Delta variant, and 57,616 infected with the Omicron variant. The methodological quality of all studies was high. The prevalence of long-COVID was higher in individuals infected with the historical variant (50%) compared to those infected with the Alpha, Delta or Omicron variants. It seems that the prevalence of long-COVID in individuals infected with the Omicron variant is the smallest, but current data are heterogeneous, and long-term data have, at this stage, an obviously shorter follow-up compared with the earlier variants. Fatigue is the most prevalent long-COVID symptom in all SARS-CoV-2 variants, but pain is likewise prevalent. The available data suggest that the infection with the Omicron variant results in fewer long-COVID symptoms compared to previous variants; however, the small number of studies and the lack of the control of cofounders, e.g., reinfections or vaccine status, in some studies limit the generality of the results. It appears that individuals infected with the historical variant are more likely to develop long-COVID symptomatology.

Protective effect of COVID-19 vaccination against long COVID syndrome: A systematic review and meta-analysis

“…Furthermore, since the follow-up durations of the surveys varied from 2 weeks to 6 months, temporary reactions following vaccination may have been included in the effect estimations. Fourth, since the observational periods of the included studies varied widely, we could not evaluate the impact of different variants of concern [41] . Additionally, the effect of three- or four-dose vaccination on long COVID could not be measured.…”

SARS-CoV-2 Affects Both Humans and Animals: What Is the Potential Transmission Risk? A Literature Review

“…Although fatigue and pain seem to be the most prevalent long-COVID symptoms, to date the association of SARS-CoV-2 with COVID symptoms is still unclear and this problem can be explained by the different variants [ 102 ]. In 2020, four main variants were considered by WHO among the VOCs (variants of concern): (1) Alpha, identified for the first time in the UK in September 2020; (2) Beta, identified for the first time in South Africa in May 2020; (3) Gamma, first identified in Brazil in November 2020; and (4) Delta, first identified in October 2020 in India [ 103 ].…”

Comparison of prevalence and evolution of COVID-19 olfactory disorders in patients infected by D614 (wild) and B.1.1.7. Alpha variant: a brief report

“…Depending on the method used for the olfactory assessment, the 12-month prevalence of persistent OD ranged from 15 to 70% [6][7][8]. The prevalence and the types of OD appeared to change over the successive severe acute respiratory syndrome coronavirus type-2 (SARS-CoV-2) variant waves but few reports are currently available and most of them focusing on clinical findings during the infection and not on long-term outcomes [9,10].…”