Table 1 Major characteristics of studies included in the systematic review

Abzhandadze²⁷

Sweden

SL

People with sickness benefits for COVID-19

11,902

Andersson³⁷

Denmark

NOD

Adults ≥ 50 years

2,430,694

Bygdell³⁶

Sweden

PCC

Adults with previous COVID-19

506,107

Bygdell³⁵

Sweden

PCC

Children with previous COVID-19

162,383

Gronkjaer³⁸

Denmark

NOD

Children and adults

4,888,615

Hedberg¹⁷

Sweden

PCC

Children & adults ≥ 1 year

473,359

Hetlevik²²

Norway

PCS

Adults

539,603

Jacobsen¹¹

Denmark

SL

Working-age population

7640

Kildegaard²¹

Denmark

HCU, PCC

Children

995,504

Lund²⁰

Denmark

HCU, NOD

Children and adults with previous COVID-19 or negative test

91,187

Magnusson²³

Norway

HCU, PCS

Children

706,885

Magnusson²⁴

Norway

PCS

Adults

1,323,145

Magnusson²⁵

Norway

PCS

Adults

2,348,831

Mkoma³³

Denmark

PCC

Adults with previous COVID-19

2,287,175

Nersesjan⁴⁰

Denmark

NOD

Adults with previous COVID-19, negative and untested controls

4,152,792

Reme³⁴

Norway

PCC

Adults (30 to 70 years) with previous COVID-19

214,667

Rømer³⁹

Denmark

NOD

Adults with previous COVID-19 and matched negative controls

2,039,204

Skei²⁸

Norway

SL

Working-age population admitted to hospital with sepsis

35,839

Skyrud¹⁸

Norway

HCU

Adults

1,401,922

Skyrud²⁶

Norway

SL

Working-age population with work contract

1,177,274

Skyrud¹⁹

Norway

HCU

Adults hospitalized for COVID-19 or other respiratory tract infections

87,288

Spetz²⁹

Sweden

SL

Working age population

37,420