covid: long covid decreased with vaccination

 An Italian observational study compared healthcare workers who developed long Covid versus not, finding that those given the Pfizer vaccine were less likely to get long Covid, and the more vaccinations the better (see covid long covid after vaccine italy JAMA2022, or doi:10.1001/jama.2022.11691) 

 

Details: 

-- 2560 healthcare workers were tested for Covid, of whom 739 had covid and 229 had long covid, from March 2020 to April 2022, in 9 Italian healthcare facilities

    -- these workers had PCR tests every 1-2 weeks or had symptoms/were exposed to Covid cases 

    -- long Covid was defined as at least one Covid-related symptom lasting at least four weeks (similar to the CDC definition) 

    -- 89 had asymptomatic infection

-- long covid vs infected without long covid: age 44 vs 41; BMI 24.3 vs 23.5

-- number of prior vaccine doses:

    -- 0 in 74 people (42%) vs 245 (58%) [many workers were infected prior to vaccines]

    -- 1 in 3 people (30%) vs 7 (70%) [note: very low numbers of people]

    -- 2 in 8 people (17%) vs 38 (83%) [note: very low numbers of people]

    -- 3 in 42 people (16%) vs 220 (84%) 

-- comorbidities, comparing regular vs long covid: allergies in 104 (37%) vs 181 (64%); cardiovasc 34 (40%) vs 51 (60%); COPD/asthma 28 (47%) vs 32 (53%); autoimmune/rheum in 21 (44%) vs 27 (56%); other comorbidities had very small numbers of people (cancer, metabolic disease, pregnancy, heme, mental health) 

-- all healthcare workers were required to have had three doses of BNT162/b2 vaccine, with the first and second doses in January to February 2021 and the booster dose in November to December 2021 [though many cases were pre-vaccine]

-- self-reported patient surveys included demographics, comorbidities, Covid-related symptoms at the time of infection and the duration of symptoms [though asymptomatic people were also included]

-- hospitalized individuals were excluded to minimize bias to severe cases 

 

Results: 

-- prevalence of long Covid varied by SARS-CoV-2 variant: 

    -- wave 1 (wild type): 41.8% (39.9%-56.2%) 

    -- wave 2 (Alpha variant): 35.9% (30.5%-41.6%) 

    -- wave 3 (Delta and Omicron variants): 16.5% (12.4%-21.4%) 

-- long Covid prevalence, by number of vaccine doses: 

    -- unvaccinated: 41.8% (37.0%-46.7%) 

    -- one vaccine dose: 3.0% (6.7%-65.2%) [note very few people were in this group, explaining the wide conference intervals] 

    -- two vaccine doses: 17.4% (7.8%-31.4%) [note very few people were in this group, explaining the wide conference intervals] 

    -- three doses: 16% (11.8%-21.0%) 

-- other factors associated with long Covid, with the reference group being wild type infection in females without vaccination, in multivariate analysis: 

    -- male sex: OR 0.65 (0.44-0.98), p=0.04 

    -- age: OR  1.23 ((1.01-1.49), p=0.04 

    -- BMI: OR 1.10 (0.92-1.31), p=0.30  (not significant)

    -- allergies: OR 1.50 (1.06-2.11), p=0.02 

    -- number of comorbidities: OR 1.3 to (1.04-1.68), p=0.03 

-- no association related to the time between the second and third dose of vaccine and long Covid, OR 0.66 (0.34-1.29) 

 

Commentary: 

-- this study adds further support for vaccination in decreasing long covid

    -- a massive UK observational study prior to the delta and omicron variants also found that there was vaccine protection from developing long covid: see http://gmodestmedblogs.blogspot.com/2022/01/covid-post-vaccine-infections-long.html

    -- another large datamining study of the VA system in the US assessed 33,940 individuals with breakthrough infections for evidence of long covid, finding that those vaccinated prior to an infection had a 15% lower risk of developing long covid than those getting SARS-CoV-2 without prior vaccination (see covid long covid breakthru infections natmed2022 in dropbox, or doi.org/10.1038/s41591-022-01840-0). This study has the limitations of a largely male cast

-- the noted decline in long covid in later SARS-CoV-2  variants has been noted before, but is this intrinsic to the variant? or is it because people have higher levels of immunity as this pandemic continues (or by some combination of infection and vaccines)?

-- for a recent CDC report on long covid, see http://gmodestmedblogs.blogspot.com/2022/06/covid-cdc-report-on-long-covid-symptoms.html 

 

Limitations:     

-- not so much granular data. did asymptomatic people have the same % of long covid? were the long covid symptoms or severity different in asymptomatics?

-- how severe were the long covid symptoms? did they affect daily living significantly/how much? Were long covid symptoms in those vaccinated milder than in unvaccinated?

-- relying on self-report may not truly be accurate. Were these spontaneous self-reports of long covid? were there specific questions (especially non-open-ended ones) asked that might have biased the results (ie leading the witness)?

-- most cases were pre-Omicron, so generalizability to the current situation is unclear

    -- as mentioned in prior blogs, we are living in an age of evidence-free medicine. by the time a study comes out (even the rapid pre-peer-reviewed pre-print ones), the world has moved on to yet another few variants, which might well have very different characteristics to the ones measured in the study. so, a bit of guess-work in terms of generalizability to the current situation. and we know from years of medical guess-work that this is not always so accurate…

 

so, further reason to still promote vaccination rigorously:

-- i expect that some of us clinicians (as well as patients) feel that covid is not so bad these days. after all, many people may have residual immunity from older vaccines, and we have the backup of Paxlovid and monoclonal antibodies to help avoid less severe cases (though admittedly not 100% so)

-- but many people still get mild or asymptomatic covid, and still get long covid

-- and many of them would not qualify for the Paxlovid/monoclonal antibodies

-- and, long covid can be devastating and long-lasting (se see http://gmodestmedblogs.blogspot.com/2022/05/covid-keeps-on-getting-longer.html ). for example,  even 4 years after the original SARS-CoV-1 epidemic 20 years ago, some had continuing symptoms...

 

geoff

 

If you would like to be on the regular email list for upcoming blogs, please contact me at gmodest@uphams.org

 

to get access to all of the blogs (2 options):

1. go to http://gmodestmedblogs.blogspot.com/ to see them in reverse chronological order

2. click on 3 parallel lines top left, if you want to see blogs by category, then click on "labels" and choose a category​

3. or you can just click on the magnifying glass on top right, then  type in a name in the search box and get all the blogs with that name in them

 

or: go to https://www.bucommunitymedicine.org/ , a website from the Community Medicine section at Boston Medical Center.  This site does have a very searchable and accessible list of my blogs (though there have been a few that did not upload over the last year or two). but overall it is much easier to view blogs and displays more at a time.

 

 

please feel free to circulate this to others. also, if you send me their emails, i can add them to the list