Table 2 Type of study designs identified for each clinical domain

Clinical phenotype and natural history of disease

1 article [18]

18 articles* [19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38]

3 articles [39,40,41]

7 articles [42,43,44,45,46,47,48]

21 articles [49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69]

27 articles [70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96]

Transmission and prevention

10 articles** [22, 29, 38, 97,98,99,100,101,102,103]

3 articles [42, 43, 104]

3 articles [61, 62, 105]

7 articles [73, 74, 83, 84, 91, 92, 106]

Diagnostics

5 articles** [19, 37, 107,108,109]

1 article [110]

2 articles [46, 111, 112]

1 article [69]

4 articles [55, 74, 82, 113]

Immune response

4 articles** [31, 32, 107, 114]

2 articles [44, 46]

6 articles [52, 65, 115,116,117,118]

9 articles [55, 70, 72, 73, 76, 86, 91,92,93]

Drug therapy and supportive care

1 article [119]

7 articles** [19, 21, 24, 38, 120,121,122]

3 articles [42, 123, 124]

8 articles [49, 51,52,53, 56, 64, 66, 125]

17 articles [55, 71, 73,74,75,76,77,78, 80, 81, 83, 85, 86, 89, 95, 96, 126]

Risk factors for more severe disease

3 articles [37, 38, 114]

1 article [44]