| Name | Info | Provider | Link |
|---|---|---|---|
| Flu | free resource | MedlinePlus Health Information | https://medlineplus.gov/flu.html |
| subscription/membership/fee required | Ovid Technologies, Inc. | http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=linkout&SEARCH=19082745.ui | |
| subscription/membership/fee required | Springer | https://doi.org/10.1007/s10654-008-9306-7 |