To the Editor—The recent report on 'co-infection of influenza B and Streptococcus' by Lam et al1 is very interesting. They reported "four cases infected with influenza B and streptococci that gave rise to severe pneumonia" and mentioned that "this is the second case report of severe invasive pneumococcal pneumonia secondary to influenza B infection."1 Indeed, both influenza B and Streptococcus infections are important infectious diseases that are encountered worldwide. In fact, there are more than two previous publications reporting the concurrent infection of influenza B and Streptococcus.2 3 In the report by Aebi et al,2 three cases were document and additional four cases were presented in the report by Scaber et al.3 Hence, the claim by Lam et al1 should not be correct. Nevertheless, in all reports, the clinical features of the pneumonia were serious and sometimes fatal. As Lam et al1 suggested, physicians should increase awareness of possible concurrent infection in the present era of emerging influenza.

1. Lam KW, Sin KC, Au SY, Yung SK. Uncommon cause of severe pneumonia: co-infection of influenza B and Streptococcus. Hong Kong Med J 2013;19:545-8. Crossref

2. Aebi T, Weisser M, Bucher E, Hirsch HH, Marsch S, Siegemund M. Co-infection of influenza B and streptococci causing severe pneumonia and septic shock in healthy women. BMC Infect Dis 2010;10:308. Crossref

3. Scaber J, Saeed S, Ihekweazu C, Efstratiou A, McCarthy N, O'Moore E. Group A streptococcal infections during the seasonal influenza outbreak 2010/11 in South East England. Euro Surveill 2011;16 pii:19780.

To the Editor—Our report concerned severe pneumonia due to co-infection of influenza B and streptococcus. Scaber et al1 described a series of 19 invasive streptococcal infection cases affecting a variety of organs. Scaber's objective and emphasis were different from that of Aebi et al2 and our report.3 Moreover, Scaber et al1 did not provide much clinical details of the patients, such as laboratory investigation findings and complications. Therefore, their article1 was not included in our reference list. We would nevertheless like to thank Drs Joob and Wiwanitkit for their comments. The mentioned studies certainly enhance awareness of this serious co-infection of influenza B and streptococcus and alert physicians and other health care professionals.

1. Scaber J, Saeed S, Ihekweazu C, Efstratiou A, McCarthy N, O'Moore E. Group A streptococcal infections during the seasonal influenza outbreak 2010/11 in South East England. Euro Surveill 2011;16 pii:19780.

2. Aebi T, Weisser M, Bucher E, Hirsch HH, Marsch S, Siegemund M. Co-infection of influenza B and streptococci causing severe pneumonia and septic shock in healthy women. BMC Infect Dis 2010;10:308. Crossref

3. Lam KW, Sin KC, Au SY, Yung SK. Uncommon cause of severe pneumonia: co-infection of influenza B and Streptococcus. Hong Kong Med J 2013;19:545-8. Crossref