الفهرس 
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Abstract
The term ”post-COVID-19 condition” is used to describe the state
experienced by individuals who have recovered from the acute phase of
COVID-19 but still exhibit lingering effects or an extended manifestation of
symptoms beyond the expected duration (more than three weeks) or even new
symptoms. This condition appears to manifest as a multisystem disease,
persisting even after a relatively mild initial illness.
Vitamin D plays a crucial role in enhancing the immune system and
regulating immune-modulatory mechanisms. Maintaining an optimal serum
level of vitamin D is associated with reduced viral infections, complications,
and the occurrence and progression of various chronic conditions. The current
study aims to assess the prevalence of post-COVID-19 symptoms and serum
vitamin D levels among participants. Additionally, it investigates the impact
of vitamin D supplementation on alleviating post-COVID-19 symptoms.
The study aimed to address its objectives through a comprehensive
approach, involving patients recruited from a post-COVID-19 outpatient clinic
at Menoufia University Hospital. The study spanned from June 1, 2021, to
April 1, 2023. It adopted a two-phase design, beginning with a cross-sectional
study for case recruitment, followed by a double-blinded, placebo-controlled
randomized clinical trial involving 111 participants with abnormal vitamin D
level. The primary objective of this interventional trial was to assess the
impact of vitamin D supplementation on post-COVID-19 symptoms. The
cross-sectional study conducted prior to the intervention facilitated the
identification and recruitment of cases.
The eligible participants were assessed using:
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Interviewing questionnaire:
Participants underwent face-to-face interviews at the post-COVID-19
outpatient clinic, utilizing a self-designed, structured, and validated Arabic
questionnaire with seven sections. The first section covered sociodemographic
data (age, gender, education, occupation, etc.). The second
section delved into risk factors for post-COVID-19 symptoms, including
medications, previous hospitalization, and long-term health conditions
(diabetes mellitus, bronchial asthma, hypertension, obesity, etc.). The third
section focused on risk factors for vitamin D deficiency, encompassing
nutritional history, sun exposure, sunscreen use, and gastrointestinal diseases.
The fourth to seventh sections comprised questions about COVID-19
infection, post-COVID-19 symptoms, functional status, mental health, fatigue,
and COVID-19 vaccination status. Post-COVID-19 symptoms were
categorized by the CDC into general, cardio-respiratory, neuropsychiatric,
gastrointestinal, and cutaneous symptoms. Severity assessment utilized the
ESAS scale, ranging from 1 to 10, with one indicating very mild and ten
signifying very severe symptoms.
Physical examination:
A comprehensive examination was conducted on all patients,
encompassing anthropometric measurements, vital signs, signs associated with
vitamin D deficiency, and possible signs related to post-COVID-19
conditions.
Laboratory investigations to assess serum vitamin D levels:
Blood samples (2 ml) were withdrawn from all participants via
venipuncture to assess the 25-hydroxy vitamin D level in the serum. Vitamin
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D levels were categorized as normal if (> 30 ng/dl), and abnormal below this
level.
Subsequently, patients with abnormal vitamin D level (111 participants)
were categorized into two groups for the randomized control phase. The case
group (56 patients) received oral vitamin D tablets for two months, while the
control group (55 patients) received a visually similar placebo for the same
duration. Both groups underwent clinical follow-up after two months, during
which participants completed the post-COVID-19 symptoms questionnaire
based on the ESAS scale to assess changes in symptom severity. The control
group received vitamin D supplementation after the follow-up stage for ethical
considerations.
The study findings reveal the following key results:
1- The prevalence of post-COVID-19 conditions was 50.32% in the
subacute period (between 4 to 12 weeks from COVID-19 infection) and
49.68% in the chronic period (after 12 weeks from COVID-19
infection).
2- Various comorbidities among post-COVID-19 participants were
examined including smoking, bronchial asthma, obesity, hypertension,
and psychiatric disease.
3- Approximately 75.48% of participants experienced three or more
persistent post-COVID-19 symptoms.
4- Different post-COVID-19 symptoms were identified, including fatigue,
sleep disturbance, poor memory, lack of concentration, headache,
myalgia, arthralgia, cough, palpitation, dyspnea, skin rash, and hair loss.
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5- Cardio-respiratory, neuropsychiatric, and musculoskeletal symptoms
exhibited greater severity during the ongoing post-COVID-19 period
compared to the chronic period (p-value <0.001).
6- A significant relationship was observed between post-COVID-19
condition types and fatigue.
7- Regarding the functional state, the chronic post-COVID-19 group
demonstrated more severe functional limitations than the ongoing
group.
8- Fatigue and headache were the most prevalent symptoms after receiving
the COVID-19 vaccine.
9- The frequency of vitamin D deficiency among the participants was
71.6%.
10- The severity of post-COVID-19 symptoms displayed a negative
correlation with vitamin D levels.
11- Concerning risk factors for vitamin D deficiency, a significant relation
excited between vitamin D deficiencies, sun exposure, and daily milk
intake.
12- Cardio-respiratory and neuropsychiatric symptoms were more frequent
among participants with vitamin D level deficiency than those with a
normal level.
13- Vitamin D supplements in the form of 2000 IU once tablet daily for
two months demonstrated an improvement in various post-COVID-19
symptoms.
The present study concluded that:
Post-COVID-19 conditions were prevalent among attendees of
Menoufia University Hospital, affecting nearly half of individuals during the
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chronic period. Notably, vitamin D deficiency was widespread among post-
COVID-19 patients, with an observed association with symptom frequency.
While vitamin D supplementation showed partial effectiveness in alleviating
symptoms, it holds promise as a potential preventive strategy for mitigating
COVID-19 sequelae. These findings underscore the importance of further
investigation into the role of vitamin D in post-COVID-19 recovery and the
potential benefits of supplementation in reducing the burden of long-term
sequelae.
Based on the findings of the current study, the following
recommendations are proposed:
1- Educate patients about the criteria and possibility of post-COVID-19
conditions.
2- Evaluate serum vitamin D levels during both COVID-19 and post-
COVID-19 periods.
3- Administer vitamin D supplementation to post-COVID-19 patients
for alleviating symptoms.
4- Consider fortifying commonly consumed foods such as milk, cheese,
margarine, rice, flour, orange juice, and cereals to effectively
enhance vitamin D intake and status among adult populations.
5- Develop a public health policy to enhance the population’s
understanding of vitamin D sources and benefits. This can be
achieved through TV advertisements, written brochures in clinics,
and ensuring the availability of different forms of vitamin D, such as
drops or tablets, in primary health care unit.