The study was led by Daniel Hwang of the University of Queensland’s Institute for Molecular Bioscience and conducted through the Global Consortium for Chemosensory Research. Investigators described the study as an attempt to examine anecdotal reports from a Facebook support group that some people experienced better smell after vaccination. Participants completed a multilingual survey, enabling the team to examine self-reported sensory changes in a geographically broad population. The analysis distinguished among different forms of chemosensory dysfunction rather than treating all symptoms as a single loss of smell or taste. These included parosmia, in which familiar odors become distorted; phantosmia, in which people smell things that are not present; and distorted taste.

Although the large majority reported no post-vaccination change, some participants said their symptoms improved after vaccination. The researchers said these reports may provide reassurance for people with persistent post-COVID sensory problems who are concerned that vaccination could worsen their condition. They also emphasized that the survey cannot establish that vaccination produced the reported improvements. Because the research was observational, natural recovery from COVID-related smell and taste problems may have contributed to the pattern. The findings therefore support an association between vaccination and mostly stable symptoms, not a causal conclusion that the vaccine altered chemosensory function in most participants.

Persistent changes in smell and taste can affect eating, nutrition, enjoyment of food and quality of life after COVID-19. The study authors said clinicians should assess different types of smell and taste dysfunction separately when counseling patients, because conditions such as parosmia and phantosmia may follow different courses. The survey results provide evidence that vaccination was not commonly followed by deterioration or improvement in the symptoms reported by this group, but its design does not determine why individual experiences differed. Earlier evidence cited in the release indicates that these symptoms have varied across the pandemic: a 2020 systematic review and meta-analysis of more than 38,000 people estimated that 43% experienced smell dysfunction and 45% experienced taste dysfunction, while a 2023 study reported a global prevalence of smell dysfunction of 3.7% with later variants. A 2025 review estimated that about 7% of participants experienced loss of smell three years after infection, underscoring the continued burden of persistent chemosensory problems.

Subject of Research: An observational survey of post-vaccination changes in smell and taste among people with persistent symptoms after COVID-19

Article Title: Vaccination has little impact on post-COVID smell and taste issues

Article References: Vaccination has little impact on post-COVID smell and taste issues. Original publication (Bibliographic details unavailable.)

Image Credits: AI Generated

DOI: Not provided

Keywords: COVID-19 vaccination, loss of smell, loss of taste, parosmia, phantosmia, chemosensory dysfunction, post-COVID symptoms, observational study, global survey, Vaccination, little, impact

Trained enumerators interviewed participants face to face for approximately 20–30 minutes and administered a structured checklist covering 25 possible daily health complaints. The total score ranged from zero to 25 and was divided into three domains: sensory function or pain, body-system function, and activity participation. Participants were eligible if they were at least 15 years old, had diagnosed diabetes and reported a previous COVID-19 infection. Vaccination status was verified using electronic records from Indonesia’s SatuSehat platform and physical vaccination cards. Missing data were addressed through K-nearest-neighbours imputation with k = 5, producing an analytic sample of 420 participants. The count outcomes were modelled with negative binomial regression adjusted for sociodemographic and clinical variables.

The participants had a median age of 60 years, and 70.2% were female. A total of 36.2% had received a COVID-19 vaccine before their infection. Joint or muscle pain was the most prevalent complaint, reported by 46.0% of participants, followed by visual impairment at 43.1% and fatigue at 24.3%. The multivariable results also identified associations between demographic or clinical characteristics and particular complaint domains. Female participants had a higher rate of total daily complaints than male participants, with an incidence rate ratio of 1.25 and a 95% confidence interval of 1.02–1.53. Participants with secondary education had a lower rate of body-system dysfunction, with an incidence rate ratio of 0.66, while the absence of other comorbidities was associated with a lower rate of sensory or pain complaints, with an incidence rate ratio of 0.84. The supplied abstract did not provide confidence intervals for these two domain-specific estimates.

Vaccination after the index COVID-19 infection was not significantly associated with a lower rate of complaints related to that infection. The estimated incidence rate ratio was 1.06, with a 95% confidence interval of 0.90–1.26, which includes no difference. This estimate does not show that vaccination after infection reduced complaints, but it also does not establish that vaccination before infection was superior to vaccination after infection. The significant pre-infection estimate and the non-significant post-infection estimate came from separate comparisons, and the reported confidence interval for the post-infection association includes both lower and higher values than one. The clearest finding was therefore the observed association between pre-infection vaccination status and the overall rate of daily complaints, rather than a demonstrated advantage of one vaccination timing over the other.

The study offers a primary-care view of health burdens reported by people with diabetes after COVID-19, a population for which evidence from low- and middle-income settings was described as limited. The authors proposed that vaccination promotion could be integrated into routine chronic-disease management in these settings, while calling for prospective confirmation of the association. Several features constrain that conclusion. The cross-sectional design assessed vaccination and infection histories retrospectively and collected the other data at a single time point, allowing the analysis to estimate rates but not establish temporal or causal relationships. The sample was drawn from one Indonesian province and included only people with self-reported prior infection, with no uninfected control group. Unmeasured differences between vaccinated and never-vaccinated participants could therefore contribute to the observed pattern, and the findings may not generalize to other populations or primary-care systems. Within these limitations, the study linked pre-infection vaccination with a lower overall burden of daily complaints among 420 Indonesian primary-care patients with diabetes after COVID-19.

Subject of Research: Association of pre-infection COVID-19 vaccination with daily health complaints among Indonesian primary-care patients with diabetes.

Article Title: Beyond the pandemic declaration: daily health complaints in diabetic COVID-19 survivors and the association with prior vaccination in Indonesian primary care

Article References: Machmud, P. B., Khatimah, H., Mahkota, R., Veronica, J., & Wijayanto, A. W. (2026). Beyond the pandemic declaration: daily health complaints in diabetic COVID-19 survivors and the association with prior vaccination in Indonesian primary care. BMC Public Health. https://doi.org/10.1186/s12889-026-30043-2

Image Credits: AI Generated

DOI: 10.1186/s12889-026-30043-2

Keywords: COVID-19 vaccination, diabetes mellitus, daily health complaints, post-COVID symptoms, cross-sectional study, primary care, Indonesia, long COVID, negative binomial regression, Beyond, pandemic, declaration

The research team recruited 21 adults aged 35 to 68, dividing them into 11 controls and 10 individuals with long COVID. Every participant had a documented history of SARS-CoV-2 infection, but the two groups differed sharply in the severity of the acute illness and in their recovery. The controls had all experienced asymptomatic or mild infections and reported no lingering symptoms. The long COVID group, by contrast, had suffered moderate-to-critical disease: 60 percent required hospitalization, 60 percent needed oxygen therapy, and one person required mechanical ventilation. At the time of testing, roughly three years after infection, they continued to report fatigue, exercise intolerance, breathlessness, and headaches, and their scores on the Post-COVID-19 Functional Status Scale indicated substantially greater functional limitation than the controls.

To disentangle the possible mechanisms behind this persistent limitation, the investigators designed a three-visit protocol that separated each measurement from the others. On the first visit, participants completed a symptom-limited cardiopulmonary exercise test on a cycle ergometer, with breath-by-breath gas exchange analysis, continuous electrocardiography, and blood pressure monitoring. The second visit was devoted to transthoracic echocardiography, including advanced speckle-tracking analyses of myocardial work. The third visit assessed endothelial function using brachial artery flow-mediated dilation, a noninvasive ultrasound technique in which a blood pressure cuff is inflated for five minutes to induce ischemia and the subsequent surge of blood upon release is used to probe how well the artery dilates. Participants abstained from caffeine, alcohol, and strenuous activity before each session to prevent interference between measurements.

The exercise testing revealed clear and quantifiable deficits. Compared with controls, the long COVID group achieved a lower peak oxygen uptake, a lower predicted peak oxygen uptake relative to reference values, and a lower oxygen uptake at the first ventilatory threshold, the point during incremental exercise where metabolism begins to shift toward anaerobic contribution. These differences carried large effect sizes, indicating that the impairment was not marginal. Because both maximal and submaximal aerobic capacity were reduced, the results suggest that everyday activities, not just athletic performance, demand more physiological effort from these individuals than from their fully recovered counterparts.

The vascular findings were even more striking. Flow-mediated dilation was dramatically lower in the long COVID group, with a Cohen’s d of 2.30, an effect size that is exceptionally large for a between-group comparison in human vascular physiology. Crucially, the team also measured the shear-rate stimulus, the frictional force that flowing blood exerts on the vessel wall and that normally triggers the endothelium to release nitric oxide and other vasodilators. Peak shear rate, the area under the shear-rate curve during the hyperemic period, and the area under the curve up to maximal vasodilation were all significantly reduced in the long COVID participants. This means the problem involves not only a blunted vasodilatory response but also a diminished hyperemic signal, a double hit to the mechanisms that normally match blood flow to metabolic demand.

The researchers took care to ensure that the difference in flow-mediated dilation was not an artifact of differing artery sizes. Allometric scaling of log-transformed baseline and peak diameters showed no significant group-by-diameter interaction, and the between-group difference remained significant after adjustment for baseline diameter. The difference also persisted after statistical adjustment for age, sex, body composition, and comorbidities, strengthening the conclusion that the vascular impairment is a genuine feature of the long COVID phenotype rather than a byproduct of the higher body mass index and obesity prevalence observed in this group.

Perhaps the most informative result came from the correlation analyses. Within the long COVID group, flow-mediated dilation was positively and significantly associated with both peak oxygen uptake and predicted peak oxygen uptake, meaning that individuals with better endothelial function tended to have better aerobic capacity. No such association appeared among the controls, whose vascular function was uniformly good. This pattern supports the idea that, in long COVID, the state of the peripheral vasculature becomes a rate-limiting factor for exercise performance, constraining oxygen delivery to skeletal muscle in a way that does not occur in healthy vasculature with reserve capacity to spare.

The heart, meanwhile, told a different story. Conventional echocardiographic measures, including left ventricular ejection fraction, volumes, and global longitudinal strain, were indistinguishable between groups, as were the myocardial work indices derived from pressure-strain analysis: global work index, global constructive work, global wasted work, and global work efficiency. Myocardial work integrates ventricular deformation with afterload and can detect subtle dysfunction that conventional parameters miss, yet even this sensitive approach found no group differences. Exploratory analyses did reveal intriguing internal patterns: in the long COVID group, lower global work index was associated with greater ventilatory drive and poorer ventilatory efficiency during exercise, and with higher body mass index, hinting at interactions between metabolic status, breathing mechanics, and cardiac mechanics that deserve further study in larger cohorts.

Taken together, the data sketch a coherent physiological account of long COVID exercise intolerance. Persistent endothelial injury after SARS-CoV-2 infection, plausibly driven by chronic inflammation, oxidative stress, and reduced nitric oxide bioavailability, compromises the ability of conduit and resistance vessels to dilate appropriately during exercise. The result is a peripheral limit on oxygen delivery that manifests as reduced aerobic capacity, while the central pump continues to function within normal limits. This peripheral mechanism aligns with earlier studies conducted one and two years after infection, but the present work extends the timeline considerably, showing that these abnormalities persist well into the third year after the acute illness.

The authors are careful to note the limitations of their study. It was observational, cross-sectional, and single-center, with a modest sample size, so the findings are hypothesis-generating rather than definitive. The long COVID cohort consisted predominantly of people with previous moderate-to-critical illness, and the controls all had prior asymptomatic or mild infection, so the results may not generalize to the full spectrum of post-COVID conditions. The cohort was also predominantly composed of individuals with overweight or obesity, and the study was not powered to detect sex or race differences. Even so, the large effect sizes and the a priori power calculation lend credibility to the central conclusion. Clinically, the work argues for evaluating vascular health, not just cardiac function, in patients with persistent post-COVID exercise intolerance, and for cardiometabolic risk management alongside structured rehabilitation. Whether improving endothelial function can restore exercise tolerance remains a critical question for future interventional trials.

Subject of Research: Persistent endothelial dysfunction and exercise intolerance in long COVID three years after SARS-CoV-2 infection

Article Title: Persistent endothelial dysfunction is associated with exercise intolerance in adults despite preserved myocardial work 3 years after SARS‐CoV‐2 infection

Article References: de Araújo Alves, C. C., Goulart, C. D. L., D'Ávila, L., de Souza Silva, B. H. E., Alves, I. M., Aguiar, B. V. S., Conde, C., Stein, R., & Cipriano, G., Jr. (2026). Persistent endothelial dysfunction is associated with exercise intolerance in adults despite preserved myocardial work 3 years after SARS‐CoV‐2 infection. Physiological Reports, 14(19), Article e71103. https://doi.org/10.14814/phy2.71103

Image Credits: AI Generated

DOI: 10.14814/phy2.71103

Keywords: long COVID, endothelial dysfunction, flow-mediated dilation, exercise intolerance, myocardial work, cardiopulmonary exercise testing, SARS-CoV-2, vascular function, peak oxygen uptake, echocardiography, nitric oxide, post-COVID condition