What are the current COVID-19 variants in Europe, their associated symptoms, and how do prevention and vaccination strategies impact risk groups and severe infection outcomes?

COVID-19 in Europe: Current Variants, Symptoms, Prevention, and High-Risk Groups

Current Symptomatology and Clinical Presentation

The most common COVID-19 symptoms in European patients include fever (45.4-77%), cough (41-67%), headache (70.3%), loss of smell (70.2%), nasal obstruction (67.8%), fatigue (63.3%), and breathlessness (37-49.3%). 1, 2

Core Respiratory and Systemic Symptoms

• Fever occurs in 45.4-77% of patients, though its absence should not exclude COVID-19 diagnosis 1, 2
• Cough (dry or productive) affects 41-67% of patients 1, 2
• Dyspnea/breathlessness develops in 37-49.3% of cases 1
• Fatigue and asthenia are reported in 20.3-63.3% of patients 1, 2
• Myalgia occurs in 62.5% of cases 2

Distinctive ENT Symptoms

• Loss of smell (anosmia) is a key distinguishing feature, occurring in 70.2% of mild-to-moderate cases and notably persisting ≥7 days after recovery in 37.5% of patients 1, 2
• Loss of taste (ageusia) affects 54.2% of patients 1, 2
• Sore throat occurs in 52.9% of cases 2
• Rhinorrhea is present in 60.1% of patients 2

Atypical Presentations

• Gastrointestinal symptoms including diarrhea, vomiting, and loss of appetite can occur, sometimes without respiratory symptoms 1, 3
• Neurological manifestations such as confusion, headache, and altered mental status may precede respiratory deterioration 1, 3
• Dermatological, ophthalmic, and cardiac symptoms can present as initial or isolated findings 1, 3

Variant-Specific Symptom Changes

Omicron vs Wild-Type/Alpha Differences

• Children <12 years (all unvaccinated) experienced more symptoms and higher severity scores during Omicron compared to wild-type/Alpha period 4
• Adults showed reduced disease duration and severity with Omicron 4
• Loss of smell/taste became significantly less common with Omicron (adjusted OR: 0.14; 95% CI 0.03-0.50) 4
• Upper respiratory symptoms, fever, and fatigue showed higher but non-significant odds with Omicron (aORs: 1.85-2.23) 4

Age and Sex Variations

• Young patients more frequently present with ear, nose, and throat complaints 2
• Elderly individuals more commonly develop fever, fatigue, and loss of appetite 2
• Female patients experience higher rates of loss of smell, headache, nasal obstruction, and fatigue 2

Symptom Specificity: COVID-19 vs Other Respiratory Infections

Loss of smell (anosmia) is the most specific symptom for COVID-19, occurring independently of nasal obstruction and rhinorrhea, unlike typical viral upper respiratory infections. 2

• The combination of anosmia with fever, cough, and fatigue provides higher specificity for COVID-19 than any single symptom 1, 2
• Typical respiratory symptoms alone (cough, rhinorrhea, sore throat) are non-specific and overlap substantially with other viral infections 3, 2
• Mean symptom duration of 11.5 ± 5.7 days in mild-to-moderate cases is longer than typical viral URIs 2

Red Flag Symptoms Requiring Immediate Evaluation

Critical Respiratory Warning Signs

• Oxygen saturation ≤93-94% on room air at sea level 5
• Respiratory rate ≥30 breaths/minute 5
• Lung infiltrates >50% on imaging 5
• PaO2/FiO2 ratio <300 mmHg indicating impaired gas exchange 5
• Severe respiratory distress with grunting or severe chest indrawing 5

Systemic Red Flags

• Shock or hypotension not attributable to sedation or other causes 5
• Altered mental status, confusion, or encephalopathy 1, 5
• Inability to maintain oral intake 5
• Fever with severe headache, neck stiffness, or photophobia suggesting HSV encephalitis or meningitis 5

Neurological Warning Signs

• CNS involvement occurs in 36.4% of all cases and 45.5% of severe cases 5
• Confusion or altered consciousness 5
• Seizures or new-onset epilepsy 5
• Acute cerebrovascular events 5
• Corticospinal tract signs and meningeal signs 5

Cardiac Red Flags

• New-onset myocarditis or pericarditis 5
• Coronary artery dilation/aneurysm 5
• New ventricular dysfunction 5
• Second or third-degree AV block 5
• Ventricular tachycardia 5

Pediatric-Specific Red Flags (MIS-C)

• Fever ≥38.0°C for ≥24 hours occurring 3-6 weeks post-infection 1, 5
• Severe cardiac illness 5
• Rash with nonpurulent conjunctivitis 5
• Shock or hypotension 5
• Elevated inflammatory markers 5

High-Risk Groups and Comorbidity Management

Primary High-Risk Populations

• Older adults >65 years face substantially higher risk for severe complications and death 1, 5
• Cardiovascular disease patients including those with hypertension require intensive monitoring 5, 6
• Diabetes mellitus patients require intensive monitoring 5, 6
• Chronic obstructive pulmonary disease patients require intensive monitoring 5, 6
• Active malignancy patients, particularly lung cancer, require intensive monitoring 5, 6
• Immunosuppressed patients from any cause require intensive monitoring 5

Exceptionally High-Risk Hematologic Malignancy Patients

Patients with hematological malignancies face mortality rates significantly higher than the general population, with severe/critical disease in 15.5-52.4% and critical disease in 6.9-14%. 1

Specific High-Risk HM Features:

• Active or progressive disease status (not in remission) 1
• Lymphoproliferative diseases (NHL, CLL, multiple myeloma) 1
• Acute leukemia and high-risk myelodysplastic syndromes 1
• Recent HSCT or CAR-T therapy 1, 5
• Neutrophil count ≤0.5 × 10⁹/L 5

Critical Management Points for HM Patients:

• Pneumonia requiring oxygen support occurs in 57-67.7% of HM patients vs much lower rates in general population 1
• Mechanical ventilation is required in 6.9-17% of cases 1
• Prolonged viral shedding is common, requiring documented SARS-CoV-2 negativity before resuming intensive chemotherapy 1
• Defer cellular therapy (HSCT, CAR-T) during active infection or persistent positivity due to high progression risk to lower respiratory tract infection and increased mortality 1

Importance of Treating Underlying Conditions

Optimal management of underlying comorbidities directly reduces COVID-19 severity and mortality risk. 6

• Cardiovascular disease control reduces risk of COVID-19-associated cardiac complications including myocarditis, arrhythmias, and thromboembolism 1, 6
• Diabetes management prevents hyperglycemic crises and reduces inflammatory response severity 6
• COPD optimization reduces baseline respiratory compromise and improves reserve for acute illness 6
• Cancer treatment continuation (when safe) maintains disease control, which is a major mortality predictor 1
• JAK2-inhibitors and TKI/BTKi should not be discontinued even in patients with active COVID-19 1

Prevention and Vaccination: Risk-Benefit Analysis

Core Prevention Measures

Strict infection control measures remain essential: hand hygiene, physical distancing, face masks (FFP2 for healthcare workers), and room ventilation. 1

• Single room isolation for diagnosed patients, avoiding positive pressure rooms 1
• Healthcare worker PPE: gloves, gowns, face shield, FFP2 mask, and careful hand disinfection 1
• Telemedicine utilization during pandemic peaks to reduce hospital visits 1

Vaccination Risk-Benefit in Current Era

The risk-benefit of vaccination has evolved with variant changes and population immunity, but vaccination remains beneficial for high-risk groups. 1, 4

Key Evidence on Vaccination Impact:

• Booster vaccination showed no additional reduction in Omicron symptom burden or duration compared to primary series in adults (P ≥0.12) 4
• Adults with vaccination (primary or booster) experienced reduced disease duration and severity with Omicron compared to unvaccinated individuals during wild-type/Alpha period 4
• Children <12 years (unvaccinated) had higher symptom burden with Omicron than adults, suggesting vaccination benefit persists in preventing severe disease 4

Current Risk-Benefit Assessment:

• High-risk groups (elderly, immunocompromised, HM patients, multiple comorbidities) maintain strong benefit from vaccination for preventing severe disease, hospitalization, and death 1
• Healthy young adults show diminishing marginal benefit from additional boosters for symptom reduction, though protection against severe disease persists 4
• Immunocompromised patients may require additional doses due to reduced immune response 1

Change in Risk-Benefit Over Time

• Initial vaccination provided substantial reduction in severe disease and mortality across all age groups 1
• Omicron variant shows intrinsically lower severity in vaccinated adults but higher severity in unvaccinated children 4
• Booster doses provide limited additional symptomatic benefit in healthy adults but remain important for high-risk populations 4
• Variant evolution toward reduced severity in vaccinated populations suggests shifting risk-benefit toward targeted vaccination of high-risk groups rather than universal boosting 4

Long-COVID Syndrome

Long-COVID affects 32.1-87.4% of patients in the general population, with symptoms persisting >4 weeks from acute phase onset. 1

Primary Long-COVID Symptoms:

• Fatigue (most common) 1
• Dyspnea 1
• Cough 1
• Chest pain 1
• Sleep disturbance 1
• Declined quality of life 1

Long-COVID in Special Populations:

• HM patients show 32.1% prevalence with median duration of 6 months post-acute phase 1
• Pediatric patients have lower incidence (1.8% at week 8) with headache (60-74%), fever (52-58%), and cough (42-49%) as most frequent symptoms 1
• Cardiovascular complications include inappropriate sinus tachycardia, POTS, atrial arrhythmia, cardiomyopathy, and thromboembolism 1

Critical Clinical Pitfalls to Avoid

• Do not dismiss COVID-19 based on absence of fever alone, as only 45.4-77% present with fever 1, 2
• Atypical presentations with isolated GI symptoms can occur without respiratory symptoms 1, 3
• Neurological symptoms may precede respiratory deterioration—monitor for confusion, headache, or altered mental status as early warning signs 1, 5, 3
• Bacterial superinfection risk increases in critically ill patients—maintain high suspicion when inflammatory markers rise or clinical status deteriorates despite appropriate COVID-19 management 5
• Loss of smell specificity should not be dismissed as "just a cold"—it is highly specific for COVID-19 2
• Prolonged viral shedding in immunocompromised patients requires documented clearance before resuming intensive treatments 1