Telomeres may influence the severity of COVID-19 and the risk of dying from the disease, particularly in women, a European conference is to hear.
A Spanish observational study to be presented at this year’s European Congress of Clinical Microbiology & Infectious Diseases (ECCMID) in Lisbon, Portugal, investigated the association between relative telomere length (RTL) at disease onset and COVID-19 mortality in 608 adults who were hospitalised with the virus during the first wave of the pandemic – March to September 2020.
Dr Ana Virseda-Berdices, María Ángeles Jiménez-Sousa and Amanda Fernández-Rodríguez from the Health Institute Carlos III, Madrid, and colleagues, collected blood samples within 20 days of COVID-19 diagnosis or hospitalisation, and genetic analysis using polymerase chain reaction (PCR) was done to measure telomere length in blood cells.
They estimated survival probabilities and used modelling to explore the association between RTL and mortality, taking into account patient characteristics.
In total, 533 patients survived and their average age was 67 years, 58% were male, 73% white, 24% Hispanic, while 75 – average age 78 years, 67% male, 77% white and 21% Hispanic – died from COVID-19.
The researchers found that in all patients, shorter telomeres were associated with an increased risk of death from COVID-19 at 30 and 90 days after hospital discharge.
After stratifying by age and gender, they found a longer RTL was associated with a 70% lower risk of dying from COVID-19 in all women at 30 days, and a 76% reduced risk of dying from the disease at 90 days.
In women aged 65 years or older, longer RTL was associated with a 78% lower risk of death from COVID-19 at 30 days, and 81% reduced risk at 90 days.
However, no significant differences were found in relative telomere length between men who survived COVID-19 and those who died of the disease.
In another study to be presented at the congress, Dr Ashley Otter and colleagues at the UK Health Security Agency (UKHSA) will tell delegates that a longer interval between primary COVID-19 vaccine doses can boost antibody production up to nine-fold.
The team measured antibody levels in blood samples taken from 5,871 UK healthcare workers who were enrolled in the UK’s SIREN study (SARS-CoV-2 Infection and Reinfection and EvaluatioN).
Out of the cohort, 3,989 had their first dose of the Pfizer/BioNTech vaccine at least 21 days earlier, while 1,882 had their second dose at least 14 days earlier.
The participants were classified by infection history as either previously having had COVID or naïve, with no history of infection. More than 99% of those who had not previously tested positive for the virus seroconverted after vaccination.
Following the first dose, those who had had previous infection had up to ten times higher antibody levels than naïve individuals, while after the second dose those with previous infection had antibody levels more than twice as high as those who had not had previous infection.
When they team analysed dosing intervals, they found that a longer dosing interval was associated with antibody levels that were up to nine times higher in naïve participants. This was more noticeable in younger participants.
Dosing interval did not affect antibody levels in those with previous infection, but a longer interval between infection and vaccination was linked to higher antibody levels.
Those who had their first dose of the vaccine eight months after an infection had antibody levels seven times higher than those who were vaccinated three months after infection. There was a plateau after eight months, which suggests eight months after primary infection may be an optimum time to receive the first vaccine in those with prior infection.
Regardless of timing between infection and vaccination, all individuals mount a very high antibody response after the second dose, according to the study.
Female participants and those from an ethnic minority were associated with significantly higher antibody titres, while immunosuppression was associated with significantly lower post-vaccination antibody responses.
Dr Otter said: “This study shows that a longer time between vaccine dose one and dose two results in higher antibody responses in naïve participants, which strongly supports the decision by JCVI and the UK government to lengthen the interval between vaccine doses.
“We’ve also shown that in those with previous infection, timing between exposure and vaccination plays a critical role in post-vaccination antibody responses. However, further research is needed to determine whether these higher antibody levels provide greater protection against COVID-19 disease and how this longer dosing interval may affect booster responses.”
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