Letter from out of the blue

Yesterday , totally out of the blue, we recieved a letter from the John Radcliffe Hospital. It was a copy of one sent to our GP regarding Herbie's recent pneumonia and empyema. It stated that

"The microbiology laboratory at the John Radcliffe Hospital reported a case of invasive pneumococcal disease but the serptype has not been identified.
The Health Protection Agency has issued the following collection of forms with this letter. Their advice is that Herb Taylor is given a single dose of pneumococcal conjugate vaccine 13 and it is recommended that the blood sample is taken a month after this dose to confirm adequate antibody response.

*sigh* ... what does it all mean...