Understanding the Differences: Long COVID (PACS) vs Post-COVID-19 Vaccination Syndrome (PCVS)

With the ongoing impact of the COVID-19 pandemic and vaccination rollouts worldwide, terms like Post-Acute COVID-19 Syndrome (PACS or “Long COVID”) and Post-COVID-19 Vaccination Syndrome (PCVS or “Post-COVIDvac-Syndrome”) are emerging to describe complex, long-lasting effects. While both conditions involve lingering symptoms, they arise from different causes and require distinct approaches to diagnosis and treatment.

Read more about PACS here

Key Differences in Cause and Onset

• Long COVID (PACS) arises from the infection with SARS-CoV-2 and manifests in a multisystemic condition that can persist for months or years after the acute infection has resolved. PACS encompasses a range of chronic symptoms, such as fatigue, muscle pain, cognitive impairments, and chest discomfort. It typically develops 3-4 weeks after the initial COVID-19 infection and can continue indefinitely.

• Post-COVID-19 Vaccination Syndrome (PCVS) is linked to adverse responses post-vaccination, especially from COVID-19 mRNA and adenovirus-based vaccines. Unlike PACS, PCVS does not stem from viral infection but rather the immune response and vaccine components. While many vaccine side effects resolve within days, PCVS symptoms may persist for weeks or months in some individuals​.

Symptom Overlap and Differences

Shared Symptoms

Both PACS and PCVS exhibit similar symptoms, including:

• Fatigue

• Brain fog

• Muscle and joint pain

• Chest pain

• Headaches

Distinguishing Symptoms

Differences in symptom profiles include:

• PACS often presents with respiratory symptoms (like breathlessness) and loss of smell or taste, reflecting the multisystemic nature of COVID-19.

• PCVS tends to show a higher incidence of cardiovascular effects (e.g., myocarditis, pericarditis) and, occasionally, neurological effects from immune reactions, including cases of vaccine-induced immune thrombotic thrombocytopenia (VITT) in adenovirus-based vaccines​.

Diagnostic Criteria

PACS

Diagnosis of PACS follows a history of confirmed COVID-19 infection, with symptoms persisting or emerging at least three months post-infection and lasting over two months without an alternative diagnosis. Screening may involve:

• Blood tests for inflammation markers

• Imaging, such as chest X-rays for respiratory issues

• Neurocognitive assessments for those with cognitive symptoms

PCVS

For PCVS, diagnosis hinges on symptom persistence following vaccination, generally within days to weeks post-dose. Identifying PCVS involves:

• Excluding acute COVID-19 infection via RT-PCR tests

• Reviewing symptoms in light of the vaccine received and onset timing

• Investigating biomarkers linked to immune response (e.g., elevated cytokine levels or presence of spike protein in the bloodstream)

Pathophysiology

• PACS involves chronic inflammation, possible autoimmune components, vascular issues, and viral persistence in some cases. Researchers have identified factors like amyloid fibrin microclots and circulating SARS-CoV-2 proteins as potential contributors.

• PCVS, on the other hand, may stem from an overactive immune response triggered by repeated exposure to spike protein antigens, which can lead to immune phenomena like myocarditis, immune imprinting, and T-cell overstimulation.

Treatment Approaches

Long COVID (PACS)

• Symptomatic Management: Anti-inflammatory diets, gentle exercise, and therapies targeting immune modulation.

• Cognitive Rehabilitation: Tailored cognitive exercises and therapies for brain fog.

• Psychological Support: Given the long-term nature of symptoms, support for mental health is vital.

PCVS

• Anti-inflammatory Support: Supplements like Omega-3s, curcumin, and Vitamin D might help mitigate inflammation.

• Cardiovascular Monitoring: Especially in patients with chest pain or suspected myocarditis.

• Specialised Care: Given the variability of symptoms, a tailored approach focusing on the specific vaccine-related response is essential.

Conclusion

PACS and PCVS reflect two complex, emerging conditions that require a nuanced approach for effective management. Recognising their distinct characteristics not only helps in diagnosis and treatment but also aids in advancing research to develop targeted therapies for both syndromes.