Post-COVID status varies by variant and vaccination status

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for coronavirus disease 2019 (COVID-19), has resulted in overwhelming pressure on public health systems struggling to cope with the influx of cases to prevent viral transmission. While COVID-19 survivors have acquired immunity to SARS-CoV-2, thereby slowing the rate of transmission and reducing the overall severity of infection, post-covid symptoms began to be recognized as evidence of a persistent and sometimes crippling disease.

A new study published in The Lancet compares post-COVID outbreaks caused by wild-type, Alpha, and Delta variants of SARS-CoV-2 among unvaccinated and vaccinated populations.

Study: Profiling post-COVID-19 status across different SARS-CoV-2 variants: a prospective longitudinal study in unvaccinated wild-type, unvaccinated alpha-variant, and vaccinated delta-variant populations. Image Credit: Starshaker / Shutterstock.com

Introduction

Long COVID is defined as symptoms that last 28 days or more from the initial positive COVID-19 test. Any symptoms that persist for 84 days or more from the first positive test are considered post-COVID.

Many studies have been conducted on long COVID symptoms due to their common occurrence and potential public health burden. The difficulty in recognizing symptoms as being due to COVID-19 is compounded by the heterogeneous nature of the disease.

In June 2022, it was estimated that around two million people had long COVID in the UK. About two-thirds of these people said their symptoms negatively affected their quality of life.

The current study used data from adults in the UK who reported symptoms using the COVID Symptom Study smartphone app from March 24, 2020 to December 8, 2021. All participants were in good physical health for at least a month before testing positive for COVID-19 and then reporting long symptoms = COVID.

The researchers categorized the participants by vaccination status and variant of infection. A prospective longitudinal design was used to identify any distinct disease patterns and profiles caused by different viral variants and vaccination status.

What did the study show?

The study included almost 10,000 people with long-term Covid. Of these, about 15% have developed post-COVID symptoms. Importantly, neither a lower prevalence nor duration of post-COVID symptoms was observed between vaccinated and unvaccinated individuals.

For the unvaccinated wild-type population, four types of post-COVID conditions were observed. Comparatively, seven and five conditions were observed in the unvaccinated Alpha population and the vaccinated Delta cohort, respectively.

Regardless of the variant, long COVID symptoms could be categorized into three different groups. These included symptoms related to cardiorespiratory organs, central nervous system (CNS), and multi-organ systemic inflammatory condition.

Cardiorespiratory symptoms were usually associated with severe shortness of breath, especially with Alpha or Delta variants. CNS symptoms included loss or reduction of sense of smell, brain fog, headache, and depression. These symptoms were generally not associated with other symptoms when caused by the Alpha or Delta variants.

Although intestinal symptoms were reported, they occurred in two or fewer phenotypes for each variant.

Post-COVID wild type

In the unvaccinated wild-type population, most individuals exhibited cardiorespiratory and CNS symptoms, followed by a cluster of symptoms related to all phenotypes. Notably, the most severe symptoms occurred in this patient population.

The third group suffered mainly from upper respiratory symptoms, including hoarseness and anosmia, with loss of appetite. The latter group also had CNS, upper respiratory, and gastrointestinal (GI) symptoms.

The second and fourth groups had the most severe and chronic symptoms. However, they did not differ significantly from the others in terms of age, sex or body mass index.

Post-COVID Alpha

In the unvaccinated alpha population, the largest group of patients had CNS symptoms, while the smaller group of 13 individuals had highly variable symptoms.

Post-COVID Delta

Post-COVID infection after Delta was primarily associated with CNS symptoms in the larger group. The smaller group also had the most severe cardiorespiratory symptoms and some systemic and gastrointestinal symptoms.

The second wild-type group was 75% more likely than all other groups to see a healthcare professional for help with their chronic symptoms. However, the third group was more likely to seek help for the post-COVID condition.

The second and fourth groups were 20-30% more likely to report that the disease seriously affected their daily life. Women were more at risk of severe impairment in daily life due to post-COVID and more likely to seek medical help.

What are the implications?

This study has demonstrated the value of numerical applications in tracing and characterizing a large-scale pandemic. The researchers attempted a new method of symptom profiling, the results of which yielded three clusters of symptoms across the variants.

These results support previous studies reporting different degrees of functional impairment among people in the general population after COVID. The same clusters of symptoms were reported in the post-COVID analysis in a cohort hospitalized with COVID.

CNS symptoms are frequently reported in patients with long-term COVID and have been correlated with certain brain imaging phenotypes. Notably, SARS-CoV-2 appears to spread through the degeneration of olfactory neurons, thus explaining the importance of smell-related symptoms.

Cardiorespiratory symptoms are often linked to lung damage. Thus, this group of long COVID patients should be closely monitored for the development of lung lesions.

The current study is the first to profile post-COVID-19 status in different SARS-CoV-2 variants and in patients with varying vaccination status.”

It is important to note that the results of the study can be generalized, as this study was conducted on a large sample covering a wide range of post-COVID symptoms.

Nevertheless, further studies that include a more representative range of the UK population are needed. Vaccine status also needs to be analyzed with greater granularity to better understand how different SARS-CoV-2 variants affect the risk of developing long COVID.

Our study suggests that future investigations of the mechanisms underlying the post-COVID-19 state should consider dividing affected individuals into different subgroups, in order to identify [underlying] process.”