letter to the LA Times: increased or reduced risk of transmission?

Here is the gist of a letter I wrote to the Los Angeles Times:


"Your 17 April 2013 article 'HIV concentrations in breast milk higher at earlier, abrupt weaning' states 'HIV-infected mothers who breast-fed exclusively longer than the first four months after birth had less risk of transmitting the virus to their babies through their milk, researchers said.'

"Here's what the Science Translational Medicine paper actually says about the risk of HIV transmission: 'Viewed from an intent-to-treat perspective, the risk of late postnatal transmission was 7.6% in the group randomized to stop breast-feeding at 4 months and 10.2% in the group randomized to continue breast-feeding (RH, 0.67; 95% CI, 0.39 to 1.15).'

"I.e., HIV-infected mothers who breast-fed exclusively longer than the first four months after birth had an increased risk of transmitting the virus to their babies through their milk."


It's true that HIV concentrations were higher in the milk collected at 4.5 months from the mothers who stopped breastfeeding at four months, but that milk was collected after the babies had stopped drinking it.   It's also true that adherence to the regimen was incomplete, which led to the "excess transmission risk" that the authors mentioned, but the fact remains that the risk was still lower in the group randomized to stop breastfeeding.

I think the culprit here is this sentence from the abstract: "This may explain the reduced risk of HIV-1 transmission associated with exclusive breast-feeding and why early weaning does not achieve the magnitude of HIV prevention predicted by models."  I think what the authors meant by "reduced" here is "reduced compared to what you would expect", but I can only come to that conclusion after having read the entire article.  STM is not an open-access journal: other readers of the LA Times (and, indeed, the science journalist that wrote the article) might not have the same opportunity I have.