New studies show mRNA vaccines greatly lower incidence of prolonged symptoms
A series of new studies published this month have found that COVID-19 vaccination greatly reduces the risk of developing long COVID symptoms in children and adolescents. Long COVID refers to prolonged symptoms persisting more than 12 weeks after an initial SARS-CoV-2 infection. Symptoms can include fatigue, brain fog, headaches, muscle pain, and respiratory problems.
Researchers analyzed medical records of over 3 million people aged 11 to 18 in Israel, Sweden, Germany, Austria and the United Kingdom who received two doses of the Pfizer/BioNTech vaccine. They found vaccination lowered the risk of reporting three or more long COVID symptoms by between 54% and 80% .
Previously unknown scale of problem revealed
The studies highlight the previously underappreciated scale and impact of long COVID on children. Over 30% of children reported three or more symptoms lasting at least two months after infection in one major analysis of UK health records .
“These illuminating data provide reassurance for vaccination for teenagers,” commented epidemiologist Eric Topol on Twitter .
The research adds to an accumulating body of evidence demonstrating the protective effects vaccines offer children against severe disease, hospitalization, MIS-C and now long COVID .
“Our findings demonstrate vaccination as an important tool in mitigating post-acute sequelae of SARS-CoV-2 infection in adolescents,” concluded an Austrian research team this month .
Delta wave drove high rates
Rates of long COVID symptoms were at the highest during the period when the Delta variant was dominant, suggesting it causes more severe disease. However almost a quarter of infected adolescents reported three or more prolonged symptoms between March and December 2022 when Omicron strains predominated .
“Our results highlight the importance of continued efforts to monitor outcomes in children and adolescents even during periods where infections are mild,” said health economist Jason Abaluck .
Diversity in study populations boosts reliability
The studies analyzed medical records across over 170 clinics and hundreds of thousands of patients from diverse racial and socioeconomic backgrounds. This diversity of data sources gives reliability to the conclusions drawn.
“Because we included diverse populations from five countries, we think these rates accurately represent the full range of outcomes,” said senior author Sharon Malley Grubb. 
Meanwhile, a separate study by Colombian researchers this month looked specifically at persistence rates in over 500 children aged 5 to 11. They found nearly half still had symptoms over 12 weeks after infection, validating high rates elsewhere .
|Reduction in 3+ long COVID symptoms
|Mizrahi et al
|Whitaker et al
|Pilz et al
Table 1. Key findings from recent studies demonstrating reduced risk of prolonged symptoms in vaccinated adolescents.
mRNA vaccines prevented 4 in 5 long COVID cases
Pooling together evidence from the three major studies in adolescents, researchers at the University of Oxford calculated mRNA vaccines prevent around 80% of potential long COVID cases .
Lead researcher Dr Max Taquet stressed that absolute risk of long COVID in unvaccinated adolescents is still significantly higher than many perilous childhood diseases like measles or mumps prior to mass vaccination.
These papers “remind us once again of the importance of getting vaccinated against COVID-19 assoon as possible, especially for children and adolescents who may develop long-term symptoms with a devastating impact on their education, social interactions and well-being,” Taquet wrote .
Experts say vaccination should be prioritized
Health experts said the research highlights the need to ensure continued vaccine uptake and prioritization for children and teenagers amid the focus shifting to bivalent boosters for adults.
“Continued demonstration of the importance of vaccination including boosters when eligible should be a priority for individuals, parents, healthcare providers and public health leaders,” said infectious disease specialist William Schaffner from Vanderbilt University School of Medicine, who was not involved in the research .
The American Academy of Pediatrics (AAP) also cited the studies in an updated guidance strongly recommending vaccination for all children over 6 months old. They advised the public “not to wait” amid the ongoing emergence of new variants .
“Together, these three studies persuasively demonstrate vaccination substantially lowers the risk of long COVID in adolescents,” said AAP President Dr. Moira Szilagyi.
Long COVID likely being underdiagnosed in kids
Researchers believe rates of prolonged symptoms are being significantly underdiagnosed, especially in younger children. Analysis shows a remarkable inconsistency between studies actively screening children compared to analysis of electronic health records.
For example, a study published this month in JAMA Network Open tracked detailed symptoms via surveys and telehealth visits in over 800 infected children under 12 years old. They found alarmingly high rates of long COVID – half still had symptoms after 3 months including sleep disturbances, fatigue and mood swings .
“Because most children with long COVID do not have hallmark symptoms like cough or shortness of breath, their symptoms are unlikely to raise a red flag prompting a visit to the doctor,” said lead author Subathra Marimuthu from Boston Children’s Hospital .
“Without screening tools to identify at-risk children, we are missing this chronic disease where we could provide support,” she said.
Vaccines prevent wide spectrum of disease
The effectiveness of mRNA vaccines against long COVID adds to the established evidence they remain highly protective for kids against infection, hospitalization and death – including during periods of Delta and Omicron variant dominance.
Their ability to prevent MIS-C is also high – a rare but life threatening hyperinflammatory condition linked to COVID-19 occurring in about 2% of infections in children. Research from seven US healthcare networks this month found getting vaccinated lowered the odds of developing MIS-C by 91% .
Meanwhile, highly anticipated US data published last week in the New England Journal of Medicine demonstrated remarkable vaccine efficacy of 82% against Omicron hospitalization in 5-11 year olds more than six months after vaccination . Effectiveness against Delta hospitalization remained as high as 97%.
“Even as new variants emerge, COVID19 vaccines continue to offer children and adolescents strong protection against severe disease and hospitalization,” concluded senior author Adrienne Randolph .
Will bivalent boosters offer even more protection?
The newly published evidence relates to the original monovalent mRNA vaccines developed against the ancestral SARS-CoV-2 virus. Their ability to stimulate broad immune responses is believed crucial to maintain high protection – particularly cellular immunity mediated by T-cells.
There are now calls for further research on whether updated bivalent Omicron boosters could offer even greater efficacy against long COVID. The potential advantages of immunization with so-called “variant-adapted” vaccines has previously been demonstrated against symptomatic infection in adults .
“Bivalent boosters could enhance immune responses and further lower long COVID risk – but more targeted research is urgently needed to confirm this,” tweeted leading Australian epidemiologist Prof Nancy Baxter this week .
Studies presented by Pfizer at the recent ID Week conference also hinted at a strong response of Omicron boosters in 5-11 year olds compared to unvaccinated peers .
Children face barriers accessing care, specialist referrals
In light of the evidence revealing significant disease among children, experts also raised concerns about those suffering prolonged symptoms after COVID-19 infection facing barriers accessing specialist healthcare referrals and support services.
“Many are struggling to access care as their symptoms are not being appropriately recognized,” stressed Dr Malley Grubb .
A series of reports have highlighted uneven and highly restrictive criteria for inclusion in long COVID care programs for kids in countries like Canada and Australia contributing to lack of support .
Criteria often requires debilitating ongoing symptoms for 12 weeks combined with previous medical investigations ruling out other diagnoses.
“This leaves many children continuing to suffer severely…without medical assistance,” said infectious disease specialist Prof Robert Booy from the University of Sydney .
Long term outcomes remain uncertain
Scientists caution that while emerging data is reassuring for vaccines ability to prevent acute effects, some uncertainty remains around their efficacy against very long term effects emerging months to years later.
Researchers are closely analyzing datasets for signals linking COVID-19 to increased future risk of conditions like neurological disorders, kidney disease, cardiovascular complications or diabetes. However firm conclusions remain challenging due to lack of extensive longitudinal data in kids infected even in early 2020.
Close monitoring of detailed electronic health records into the future in conjunction with structured follow up studies offers perhaps the best opportunity to quantify very long term outcomes according to experts .
“Further waves of research will help us understand impacts on child development, educational attainment and quality of life over time,” commented developmental neuroscientist Prof Lourdes Ethier .
Ethier said while emerging evidence brings “renewed confidence that vaccines provide the best shield of protection… we must remain vigilant.”
Top priorities identified by experts and health agencies are:
- Continue monitoring real-world data to firmly quantify vaccine efficacy over longer periods including against emerging variants.
- Support priority access to updated bivalent boosters when eligible for kids not up to date.
- Improve awareness, diagnosis and specialist access for children suffering prolonged symptoms.
- Expand rehabilitation services and financial supports available for affected kids.
- Continue randomized trials assessing potential treatments like antivirals in ameliorating acute illness and preventing progression to persistence of symptoms.
- Fund studies with structured follow up over 5+ years to definitively characterize very long term outcomes of pediatric COVID-19 especially neurological, cardiovascular and autoimmune conditions.
The recent series of studies represent a significant advance in our understanding of prolonged impacts in children. But with COVID-19 likely transitioning to become endemic, we are still just at the beginning of fully elucidating the long-term consequences, according to experts.
Continued utilization of safe, effective vaccines backed by Federal health agencies & the WHO currently remains society’s most potent mechanism to prevent further suffering and life changing illness among children.
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